[memory refactor][1/n] Rename Memory -> VectorIO, MemoryBanks -> VectorDBs (#828)

See https://github.com/meta-llama/llama-stack/issues/827 for the broader
design.

This is the first part:

- delete other kinds of memory banks (keyvalue, keyword, graph) for now;
we will introduce a keyvalue store API as part of this design but not
use it in the RAG tool yet.
- renaming of the APIs

llama_stack/apis/vector_dbs/__init__.py

@@ -0,0 +1,7 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from .vector_dbs import *  # noqa: F401 F403

llama_stack/apis/vector_dbs/vector_dbs.py

@@ -0,0 +1,66 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from typing import List, Literal, Optional, Protocol, runtime_checkable
+
+from llama_models.schema_utils import json_schema_type, webmethod
+from pydantic import BaseModel
+
+from llama_stack.apis.resource import Resource, ResourceType
+from llama_stack.providers.utils.telemetry.trace_protocol import trace_protocol
+
+
+@json_schema_type
+class VectorDB(Resource):
+    type: Literal[ResourceType.vector_db.value] = ResourceType.vector_db.value
+
+    embedding_model: str
+    embedding_dimension: int
+
+    @property
+    def vector_db_id(self) -> str:
+        return self.identifier
+
+    @property
+    def provider_vector_db_id(self) -> str:
+        return self.provider_resource_id
+
+
+class VectorDBInput(BaseModel):
+    vector_db_id: str
+    embedding_model: str
+    embedding_dimension: int
+    provider_vector_db_id: Optional[str] = None
+
+
+class ListVectorDBsResponse(BaseModel):
+    data: List[VectorDB]
+
+
+@runtime_checkable
+@trace_protocol
+class VectorDBs(Protocol):
+    @webmethod(route="/vector-dbs", method="GET")
+    async def list_vector_dbs(self) -> ListVectorDBsResponse: ...
+
+    @webmethod(route="/vector-dbs/{vector_db_id}", method="GET")
+    async def get_vector_db(
+        self,
+        vector_db_id: str,
+    ) -> Optional[VectorDB]: ...
+
+    @webmethod(route="/vector-dbs", method="POST")
+    async def register_vector_db(
+        self,
+        vector_db_id: str,
+        embedding_model: str,
+        embedding_dimension: Optional[int] = 384,
+        provider_id: Optional[str] = None,
+        provider_vector_db_id: Optional[str] = None,
+    ) -> VectorDB: ...
+
+    @webmethod(route="/vector-dbs/{vector_db_id}", method="DELETE")
+    async def unregister_vector_db(self, vector_db_id: str) -> None: ...