feat(api): Add Vector Store File batches api stub (#3615)

# What does this PR do?
Adding api stubs for vector store file batches apis
https://github.com/llamastack/llama-stack/issues/3533
API Ref:
https://platform.openai.com/docs/api-reference/vector-stores-file-batches

## Test Plan
CI

llama_stack/apis/vector_io/vector_io.py

@@ -318,7 +318,8 @@ class VectorStoreChunkingStrategyStatic(BaseModel):
 
 
 VectorStoreChunkingStrategy = Annotated[
-    VectorStoreChunkingStrategyAuto | VectorStoreChunkingStrategyStatic, Field(discriminator="type")
+    VectorStoreChunkingStrategyAuto | VectorStoreChunkingStrategyStatic,
+    Field(discriminator="type"),
 ]
 register_schema(VectorStoreChunkingStrategy, name="VectorStoreChunkingStrategy")
 
@@ -427,6 +428,44 @@ class VectorStoreFileDeleteResponse(BaseModel):
     deleted: bool = True
 
 
+@json_schema_type
+class VectorStoreFileBatchObject(BaseModel):
+    """OpenAI Vector Store File Batch object.
+
+    :param id: Unique identifier for the file batch
+    :param object: Object type identifier, always "vector_store.file_batch"
+    :param created_at: Timestamp when the file batch was created
+    :param vector_store_id: ID of the vector store containing the file batch
+    :param status: Current processing status of the file batch
+    :param file_counts: File processing status counts for the batch
+    """
+
+    id: str
+    object: str = "vector_store.file_batch"
+    created_at: int
+    vector_store_id: str
+    status: VectorStoreFileStatus
+    file_counts: VectorStoreFileCounts
+
+
+@json_schema_type
+class VectorStoreFilesListInBatchResponse(BaseModel):
+    """Response from listing files in a vector store file batch.
+
+    :param object: Object type identifier, always "list"
+    :param data: List of vector store file objects in the batch
+    :param first_id: (Optional) ID of the first file in the list for pagination
+    :param last_id: (Optional) ID of the last file in the list for pagination
+    :param has_more: Whether there are more files available beyond this page
+    """
+
+    object: str = "list"
+    data: list[VectorStoreFileObject]
+    first_id: str | None = None
+    last_id: str | None = None
+    has_more: bool = False
+
+
 class VectorDBStore(Protocol):
     def get_vector_db(self, vector_db_id: str) -> VectorDB | None: ...
 
@@ -529,7 +568,11 @@ class VectorIO(Protocol):
         """
         ...
 
-    @webmethod(route="/vector_stores/{vector_store_id}", method="POST", level=LLAMA_STACK_API_V1)
+    @webmethod(
+        route="/vector_stores/{vector_store_id}",
+        method="POST",
+        level=LLAMA_STACK_API_V1,
+    )
     async def openai_update_vector_store(
         self,
         vector_store_id: str,
@@ -547,7 +590,11 @@ class VectorIO(Protocol):
         """
         ...
 
-    @webmethod(route="/vector_stores/{vector_store_id}", method="DELETE", level=LLAMA_STACK_API_V1)
+    @webmethod(
+        route="/vector_stores/{vector_store_id}",
+        method="DELETE",
+        level=LLAMA_STACK_API_V1,
+    )
     async def openai_delete_vector_store(
         self,
         vector_store_id: str,
@@ -559,7 +606,11 @@ class VectorIO(Protocol):
         """
         ...
 
-    @webmethod(route="/vector_stores/{vector_store_id}/search", method="POST", level=LLAMA_STACK_API_V1)
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/search",
+        method="POST",
+        level=LLAMA_STACK_API_V1,
+    )
     async def openai_search_vector_store(
         self,
         vector_store_id: str,
@@ -568,7 +619,9 @@ class VectorIO(Protocol):
         max_num_results: int | None = 10,
         ranking_options: SearchRankingOptions | None = None,
         rewrite_query: bool | None = False,
-        search_mode: str | None = "vector",  # Using str instead of Literal due to OpenAPI schema generator limitations
+        search_mode: (
+            str | None
+        ) = "vector",  # Using str instead of Literal due to OpenAPI schema generator limitations
     ) -> VectorStoreSearchResponsePage:
         """Search for chunks in a vector store.
 
@@ -585,7 +638,11 @@ class VectorIO(Protocol):
         """
         ...
 
-    @webmethod(route="/vector_stores/{vector_store_id}/files", method="POST", level=LLAMA_STACK_API_V1)
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/files",
+        method="POST",
+        level=LLAMA_STACK_API_V1,
+    )
     async def openai_attach_file_to_vector_store(
         self,
         vector_store_id: str,
@@ -603,7 +660,11 @@ class VectorIO(Protocol):
         """
         ...
 
-    @webmethod(route="/vector_stores/{vector_store_id}/files", method="GET", level=LLAMA_STACK_API_V1)
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/files",
+        method="GET",
+        level=LLAMA_STACK_API_V1,
+    )
     async def openai_list_files_in_vector_store(
         self,
         vector_store_id: str,
@@ -625,7 +686,11 @@ class VectorIO(Protocol):
         """
         ...
 
-    @webmethod(route="/vector_stores/{vector_store_id}/files/{file_id}", method="GET", level=LLAMA_STACK_API_V1)
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/files/{file_id}",
+        method="GET",
+        level=LLAMA_STACK_API_V1,
+    )
     async def openai_retrieve_vector_store_file(
         self,
         vector_store_id: str,
@@ -657,7 +722,11 @@ class VectorIO(Protocol):
         """
         ...
 
-    @webmethod(route="/vector_stores/{vector_store_id}/files/{file_id}", method="POST", level=LLAMA_STACK_API_V1)
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/files/{file_id}",
+        method="POST",
+        level=LLAMA_STACK_API_V1,
+    )
     async def openai_update_vector_store_file(
         self,
         vector_store_id: str,
@@ -673,7 +742,11 @@ class VectorIO(Protocol):
         """
         ...
 
-    @webmethod(route="/vector_stores/{vector_store_id}/files/{file_id}", method="DELETE", level=LLAMA_STACK_API_V1)
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/files/{file_id}",
+        method="DELETE",
+        level=LLAMA_STACK_API_V1,
+    )
     async def openai_delete_vector_store_file(
         self,
         vector_store_id: str,
@@ -686,3 +759,89 @@ class VectorIO(Protocol):
         :returns: A VectorStoreFileDeleteResponse indicating the deletion status.
         """
         ...
+
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/file_batches",
+        method="POST",
+        level=LLAMA_STACK_API_V1,
+    )
+    async def openai_create_vector_store_file_batch(
+        self,
+        vector_store_id: str,
+        file_ids: list[str],
+        attributes: dict[str, Any] | None = None,
+        chunking_strategy: VectorStoreChunkingStrategy | None = None,
+    ) -> VectorStoreFileBatchObject:
+        """Create a vector store file batch.
+
+        :param vector_store_id: The ID of the vector store to create the file batch for.
+        :param file_ids: A list of File IDs that the vector store should use.
+        :param attributes: (Optional) Key-value attributes to store with the files.
+        :param chunking_strategy: (Optional) The chunking strategy used to chunk the file(s). Defaults to auto.
+        :returns: A VectorStoreFileBatchObject representing the created file batch.
+        """
+        ...
+
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/file_batches/{batch_id}",
+        method="GET",
+        level=LLAMA_STACK_API_V1,
+    )
+    async def openai_retrieve_vector_store_file_batch(
+        self,
+        batch_id: str,
+        vector_store_id: str,
+    ) -> VectorStoreFileBatchObject:
+        """Retrieve a vector store file batch.
+
+        :param batch_id: The ID of the file batch to retrieve.
+        :param vector_store_id: The ID of the vector store containing the file batch.
+        :returns: A VectorStoreFileBatchObject representing the file batch.
+        """
+        ...
+
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/file_batches/{batch_id}/files",
+        method="GET",
+        level=LLAMA_STACK_API_V1,
+    )
+    async def openai_list_files_in_vector_store_file_batch(
+        self,
+        batch_id: str,
+        vector_store_id: str,
+        after: str | None = None,
+        before: str | None = None,
+        filter: str | None = None,
+        limit: int | None = 20,
+        order: str | None = "desc",
+    ) -> VectorStoreFilesListInBatchResponse:
+        """Returns a list of vector store files in a batch.
+
+        :param batch_id: The ID of the file batch to list files from.
+        :param vector_store_id: The ID of the vector store containing the file batch.
+        :param after: A cursor for use in pagination. `after` is an object ID that defines your place in the list.
+        :param before: A cursor for use in pagination. `before` is an object ID that defines your place in the list.
+        :param filter: Filter by file status. One of in_progress, completed, failed, cancelled.
+        :param limit: A limit on the number of objects to be returned. Limit can range between 1 and 100, and the default is 20.
+        :param order: Sort order by the `created_at` timestamp of the objects. `asc` for ascending order and `desc` for descending order.
+        :returns: A VectorStoreFilesListInBatchResponse containing the list of files in the batch.
+        """
+        ...
+
+    @webmethod(
+        route="/vector_stores/{vector_store_id}/file_batches/{batch_id}/cancel",
+        method="POST",
+        level=LLAMA_STACK_API_V1,
+    )
+    async def openai_cancel_vector_store_file_batch(
+        self,
+        batch_id: str,
+        vector_store_id: str,
+    ) -> VectorStoreFileBatchObject:
+        """Cancels a vector store file batch.
+
+        :param batch_id: The ID of the file batch to cancel.
+        :param vector_store_id: The ID of the vector store containing the file batch.
+        :returns: A VectorStoreFileBatchObject representing the cancelled file batch.
+        """
+        ...