chore(refact): move paginate_records fn outside of datasetio (#2137)

# What does this PR do?

Move under utils.

Signed-off-by: Sébastien Han <seb@redhat.com>

llama_stack/providers/utils/pagination.py

@@ -0,0 +1,43 @@
+# 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
+
+from llama_stack.apis.common.responses import PaginatedResponse
+
+
+def paginate_records(
+    records: list[dict[str, Any]],
+    start_index: int | None = None,
+    limit: int | None = None,
+) -> PaginatedResponse:
+    """Helper function to handle pagination of records consistently across implementations.
+    Inspired by stripe's pagination: https://docs.stripe.com/api/pagination
+
+    :param records: List of records to paginate
+    :param start_index: The starting index (0-based). If None, starts from beginning.
+    :param limit: Number of items to return. If None or -1, returns all items.
+    :return: PaginatedResponse with the paginated data
+    """
+    # Handle special case for fetching all rows
+    if limit is None or limit == -1:
+        return PaginatedResponse(
+            data=records,
+            has_more=False,
+        )
+
+    # Use offset-based pagination
+    start_index = start_index or 0
+    end_index = min(start_index + limit, len(records))
+    page_data = records[start_index:end_index]
+
+    # Calculate if there are more records
+    has_more = end_index < len(records)
+
+    return PaginatedResponse(
+        data=page_data,
+        has_more=has_more,
+    )