feat(dataset api): (1.4/n) fix resolver signature mismatch (#1658)

# What does this PR do?
- fix datasets api signature mis-match so that llama stack run can start

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan
```
llama stack run
```
<img width="626" alt="image"
src="https://github.com/user-attachments/assets/59072d1a-ccb6-453a-80e8-d87419896c41"
/>


[//]: # (## Documentation)

llama_stack/distribution/routers/routers.py

@@ -12,7 +12,8 @@ from llama_stack.apis.common.content_types import (
     InterleavedContent,
     InterleavedContentItem,
 )
-from llama_stack.apis.datasetio import DatasetIO, PaginatedRowsResult
+from llama_stack.apis.datasetio import DatasetIO, IterrowsResponse
+from llama_stack.apis.datasets import DatasetPurpose, DataSource
 from llama_stack.apis.eval import (
     BenchmarkConfig,
     Eval,
@@ -160,7 +161,11 @@ class InferenceRouter(Inference):
         await self.routing_table.register_model(model_id, provider_model_id, provider_id, metadata, model_type)
 
     def _construct_metrics(
-        self, prompt_tokens: int, completion_tokens: int, total_tokens: int, model: Model
+        self,
+        prompt_tokens: int,
+        completion_tokens: int,
+        total_tokens: int,
+        model: Model,
     ) -> List[MetricEvent]:
         """Constructs a list of MetricEvent objects containing token usage metrics.
 
@@ -298,7 +303,12 @@ class InferenceRouter(Inference):
                             completion_text += chunk.event.delta.text
                     if chunk.event.event_type == ChatCompletionResponseEventType.complete:
                         completion_tokens = await self._count_tokens(
-                            [CompletionMessage(content=completion_text, stop_reason=StopReason.end_of_turn)],
+                            [
+                                CompletionMessage(
+                                    content=completion_text,
+                                    stop_reason=StopReason.end_of_turn,
+                                )
+                            ],
                             tool_config.tool_prompt_format,
                         )
                         total_tokens = (prompt_tokens or 0) + (completion_tokens or 0)
@@ -471,21 +481,36 @@ class DatasetIORouter(DatasetIO):
         logger.debug("DatasetIORouter.shutdown")
         pass
 
-    async def get_rows_paginated(
+    async def register_dataset(
+        self,
+        purpose: DatasetPurpose,
+        source: DataSource,
+        metadata: Optional[Dict[str, Any]] = None,
+        dataset_id: Optional[str] = None,
+    ) -> None:
+        logger.debug(
+            f"DatasetIORouter.register_dataset: {purpose=} {source=} {metadata=} {dataset_id=}",
+        )
+        await self.routing_table.register_dataset(
+            purpose=purpose,
+            source=source,
+            metadata=metadata,
+            dataset_id=dataset_id,
+        )
+
+    async def iterrows(
         self,
         dataset_id: str,
-        rows_in_page: int,
-        page_token: Optional[str] = None,
-        filter_condition: Optional[str] = None,
-    ) -> PaginatedRowsResult:
+        start_index: Optional[int] = None,
+        limit: Optional[int] = None,
+    ) -> IterrowsResponse:
         logger.debug(
-            f"DatasetIORouter.get_rows_paginated: {dataset_id}, rows_in_page={rows_in_page}",
+            f"DatasetIORouter.iterrows: {dataset_id}, {start_index=} {limit=}",
         )
-        return await self.routing_table.get_provider_impl(dataset_id).get_rows_paginated(
+        return await self.routing_table.get_provider_impl(dataset_id).iterrows(
             dataset_id=dataset_id,
-            rows_in_page=rows_in_page,
-            page_token=page_token,
-            filter_condition=filter_condition,
+            start_index=start_index,
+            limit=limit,
         )
 
     async def append_rows(self, dataset_id: str, rows: List[Dict[str, Any]]) -> None: