fix!: update eval-tasks -> benchmarks (#1032)

# What does this PR do?

- Update `/eval-tasks` to `/benchmarks`
- ⚠️ Remove differentiation between `app` v.s. `benchmark` eval task
config. Now we only have `BenchmarkConfig`. The overloaded `benchmark`
is confusing and do not add any value. Backward compatibility is being
kept as the "type" is not being used anywhere.

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

## Test Plan
- This change is backward compatible 
- Run notebook test with

```
pytest -v -s --nbval-lax ./docs/getting_started.ipynb
pytest -v -s --nbval-lax ./docs/notebooks/Llama_Stack_Benchmark_Evals.ipynb
```

<img width="846" alt="image"
src="https://github.com/user-attachments/assets/d2fc06a7-593a-444f-bc1f-10ab9b0c843d"
/>



[//]: # (## Documentation)
[//]: # (- [ ] Added a Changelog entry if the change is significant)

---------

Signed-off-by: Ihar Hrachyshka <ihar.hrachyshka@gmail.com>
Signed-off-by: Ben Browning <bbrownin@redhat.com>
Signed-off-by: Sébastien Han <seb@redhat.com>
Signed-off-by: reidliu <reid201711@gmail.com>
Co-authored-by: Ihar Hrachyshka <ihar.hrachyshka@gmail.com>
Co-authored-by: Ben Browning <ben324@gmail.com>
Co-authored-by: Sébastien Han <seb@redhat.com>
Co-authored-by: Reid <61492567+reidliu41@users.noreply.github.com>
Co-authored-by: reidliu <reid201711@gmail.com>
Co-authored-by: Yuan Tang <terrytangyuan@gmail.com>

llama_stack/apis/benchmarks/__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 .benchmarks import *  # noqa: F401 F403

llama_stack/apis/benchmarks/benchmarks.py

@@ -0,0 +1,86 @@
+# 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, Literal, Optional, Protocol, runtime_checkable
+
+from llama_models.schema_utils import json_schema_type, webmethod
+from pydantic import BaseModel, Field
+
+from llama_stack.apis.resource import Resource, ResourceType
+
+
+class CommonBenchmarkFields(BaseModel):
+    dataset_id: str
+    scoring_functions: List[str]
+    metadata: Dict[str, Any] = Field(
+        default_factory=dict,
+        description="Metadata for this evaluation task",
+    )
+
+
+@json_schema_type
+class Benchmark(CommonBenchmarkFields, Resource):
+    type: Literal[ResourceType.benchmark.value] = ResourceType.benchmark.value
+
+    @property
+    def benchmark_id(self) -> str:
+        return self.identifier
+
+    @property
+    def provider_benchmark_id(self) -> str:
+        return self.provider_resource_id
+
+
+class BenchmarkInput(CommonBenchmarkFields, BaseModel):
+    benchmark_id: str
+    provider_id: Optional[str] = None
+    provider_benchmark_id: Optional[str] = None
+
+
+class ListBenchmarksResponse(BaseModel):
+    data: List[Benchmark]
+
+
+@runtime_checkable
+class Benchmarks(Protocol):
+    @webmethod(route="/eval/benchmarks", method="GET")
+    async def list_benchmarks(self) -> ListBenchmarksResponse: ...
+
+    @webmethod(route="/eval/benchmarks/{benchmark_id}", method="GET")
+    async def get_benchmark(
+        self,
+        benchmark_id: str,
+    ) -> Optional[Benchmark]: ...
+
+    @webmethod(route="/eval/benchmarks", method="POST")
+    async def register_benchmark(
+        self,
+        benchmark_id: str,
+        dataset_id: str,
+        scoring_functions: List[str],
+        provider_benchmark_id: Optional[str] = None,
+        provider_id: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+    ) -> None: ...
+
+    @webmethod(route="/eval-tasks", method="GET")
+    async def DEPRECATED_list_eval_tasks(self) -> ListBenchmarksResponse: ...
+
+    @webmethod(route="/eval-tasks/{task_id}", method="GET")
+    async def DEPRECATED_get_eval_task(
+        self,
+        eval_task_id: str,
+    ) -> Optional[Benchmark]: ...
+
+    @webmethod(route="/eval-tasks", method="POST")
+    async def DEPRECATED_register_eval_task(
+        self,
+        eval_task_id: str,
+        dataset_id: str,
+        scoring_functions: List[str],
+        provider_benchmark_id: Optional[str] = None,
+        provider_id: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+    ) -> None: ...