feat: add list responses API (#2233)

# What does this PR do?
This is not part of the official OpenAI API, but we'll use this for the
logs UI.
In order to support more filtering options, I'm adopting the newly
introduced sql store in in place of the kv store.

## Test Plan
Added integration/unit tests.

tests/integration/agents/test_openai_responses.py

@@ -0,0 +1,97 @@
+# 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 urllib.parse import urljoin
+
+import pytest
+import requests
+from openai import OpenAI
+
+from llama_stack.distribution.library_client import LlamaStackAsLibraryClient
+
+
+@pytest.fixture
+def openai_client(client_with_models):
+    base_url = f"{client_with_models.base_url}/v1/openai/v1"
+    return OpenAI(base_url=base_url, api_key="bar")
+
+
+@pytest.mark.parametrize(
+    "stream",
+    [
+        True,
+        False,
+    ],
+)
+@pytest.mark.parametrize(
+    "tools",
+    [
+        [],
+        [
+            {
+                "type": "function",
+                "name": "get_weather",
+                "description": "Get the weather in a given city",
+                "parameters": {
+                    "type": "object",
+                    "properties": {
+                        "city": {"type": "string", "description": "The city to get the weather for"},
+                    },
+                },
+            }
+        ],
+    ],
+)
+def test_responses_store(openai_client, client_with_models, text_model_id, stream, tools):
+    if isinstance(client_with_models, LlamaStackAsLibraryClient):
+        pytest.skip("OpenAI responses are not supported when testing with library client yet.")
+
+    client = openai_client
+    message = "What's the weather in Tokyo?" + (
+        " YOU MUST USE THE get_weather function to get the weather." if tools else ""
+    )
+    response = client.responses.create(
+        model=text_model_id,
+        input=[
+            {
+                "role": "user",
+                "content": message,
+            }
+        ],
+        stream=stream,
+        tools=tools,
+    )
+    if stream:
+        # accumulate the streamed content
+        content = ""
+        response_id = None
+        for chunk in response:
+            if response_id is None:
+                response_id = chunk.response.id
+            if not tools:
+                if chunk.type == "response.completed":
+                    response_id = chunk.response.id
+                    content = chunk.response.output[0].content[0].text
+    else:
+        response_id = response.id
+        if not tools:
+            content = response.output[0].content[0].text
+
+    # list responses is not available in the SDK
+    url = urljoin(str(client.base_url), "responses")
+    response = requests.get(url, headers={"Authorization": f"Bearer {client.api_key}"})
+    assert response.status_code == 200
+    data = response.json()["data"]
+    assert response_id in [r["id"] for r in data]
+
+    # test retrieve response
+    retrieved_response = client.responses.retrieve(response_id)
+    assert retrieved_response.id == response_id
+    assert retrieved_response.model == text_model_id
+    if tools:
+        assert retrieved_response.output[0].type == "function_call"
+    else:
+        assert retrieved_response.output[0].content[0].text == content