[Evals API][2/n] datasets / datasetio meta-reference implementation (#288)

* skeleton dataset / datasetio

* dataset datasetio

* config

* address comments

* delete dataset_utils

* address comments

* naming fix

llama_stack/distribution/routers/routers.py

@@ -6,11 +6,13 @@
 
 from typing import Any, AsyncGenerator, Dict, List
 
+from llama_stack.apis.datasetio.datasetio import DatasetIO
 from llama_stack.distribution.datatypes import RoutingTable
 
 from llama_stack.apis.memory import *  # noqa: F403
 from llama_stack.apis.inference import *  # noqa: F403
 from llama_stack.apis.safety import *  # noqa: F403
+from llama_stack.apis.datasetio import *  # noqa: F403
 
 
 class MemoryRouter(Memory):
@@ -160,3 +162,33 @@ class SafetyRouter(Safety):
             messages=messages,
             params=params,
         )
+
+
+class DatasetIORouter(DatasetIO):
+    def __init__(
+        self,
+        routing_table: RoutingTable,
+    ) -> None:
+        self.routing_table = routing_table
+
+    async def initialize(self) -> None:
+        pass
+
+    async def shutdown(self) -> None:
+        pass
+
+    async def get_rows_paginated(
+        self,
+        dataset_id: str,
+        rows_in_page: int,
+        page_token: Optional[str] = None,
+        filter_condition: Optional[str] = None,
+    ) -> PaginatedRowsResult:
+        return await self.routing_table.get_provider_impl(
+            dataset_id
+        ).get_rows_paginated(
+            dataset_id=dataset_id,
+            rows_in_page=rows_in_page,
+            page_token=page_token,
+            filter_condition=filter_condition,
+        )