feat: Add responses and safety impl extra_body (#3781)

# What does this PR do?

Have closed the previous PR due to merge conflicts with multiple PRs
Addressed all comments from
https://github.com/llamastack/llama-stack/pull/3768 (sorry for carrying
over to this one)


## Test Plan
Added UTs and integration tests

tests/integration/responses/test_extra_body_shields.py

@@ -1,34 +0,0 @@
-# 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.
-
-"""
-Test for extra_body parameter support with shields example.
-
-This test demonstrates that parameters marked with ExtraBodyField annotation
-can be passed via extra_body in the client SDK and are received by the
-server-side implementation.
-"""
-
-import pytest
-from llama_stack_client import APIStatusError
-
-
-@pytest.mark.xfail(reason="Shields are not yet implemented inside responses")
-def test_shields_via_extra_body(compat_client, text_model_id):
-    """Test that shields parameter is received by the server and raises NotImplementedError."""
-
-    # Test with shields as list of strings (shield IDs)
-    with pytest.raises((APIStatusError, NotImplementedError)) as exc_info:
-        compat_client.responses.create(
-            model=text_model_id,
-            input="What is the capital of France?",
-            stream=False,
-            extra_body={"shields": ["test-shield-1", "test-shield-2"]},
-        )
-
-    # Verify the error message indicates shields are not implemented
-    error_message = str(exc_info.value)
-    assert "not yet implemented" in error_message.lower() or "not implemented" in error_message.lower()