[Evals API] [1/n] Initial API (#287)

* type system api

* datasets api

* fix

* datasetio api

* kill reward scoring

* scoring functions + evals

* move jobs, fix errors

llama_stack/apis/datasetio/datasetio.py

@@ -0,0 +1,39 @@
+# 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 Any, Dict, List, Optional, Protocol, runtime_checkable
+
+from llama_models.schema_utils import json_schema_type, webmethod
+from pydantic import BaseModel
+
+from llama_stack.apis.datasets import *  # noqa: F403
+
+
+@json_schema_type
+class PaginatedRowsResult(BaseModel):
+    # the rows obey the DatasetSchema for the given dataset
+    rows: List[Dict[str, Any]]
+    total_count: int
+    next_page_token: Optional[str] = None
+
+
+class DatasetStore(Protocol):
+    def get_dataset(self, identifier: str) -> DatasetDefWithProvider: ...
+
+
+@runtime_checkable
+class DatasetIO(Protocol):
+    # keeping for aligning with inference/safety, but this is not used
+    dataset_store: DatasetStore
+
+    @webmethod(route="/dataio/get_rows_paginated")
+    async def get_rows_paginated(
+        self,
+        dataset_id: str,
+        rows_in_page: int,
+        page_token: Optional[str] = None,
+        filter_condition: Optional[str] = None,
+    ) -> PaginatedRowsResult: ...