[Frontend] OpenAI Responses API supports Tool/Function calling

Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>

Author: chaunceyjiang

vllm/entrypoints/openai/serving_engine.py

@@ -1055,7 +1055,7 @@ def _get_model_name(self,
 
     def _get_tool_parser(
         self,
-        tool_parser_name: str,
+        tool_parser_name: Optional[str] = None,
         enable_auto_tools: bool = False
     ) -> Optional[Callable[[AnyTokenizer], ToolParser]]:
         """Get the tool parser based on the name."""