feat(responses): add include parameter (#3115)

Well our Responses tests use it so we better include it in the API, no?

I discovered it because I want to make sure `llama-stack-client` can be
used always instead of `openai-python` as the client (we do want to be
_truly_ compatible.)

docs/_static/llama-stack-spec.html

@@ -8515,6 +8515,13 @@
                             "$ref": "#/components/schemas/OpenAIResponseInputTool"
                         }
                     },
+                    "include": {
+                        "type": "array",
+                        "items": {
+                            "type": "string"
+                        },
+                        "description": "(Optional) Additional fields to include in the response."
+                    },
                     "max_infer_iters": {
                         "type": "integer"
                     }