1. Allow developers to specify output schema and tools together.
2. If both are specified, do the following:
2.1 Do not set output schema on the model config
2.2 Add a special tool called set_model_response(result)
2.3 `result` has the same schema as the requested output_schema
2.4 Instruct the model to use set_model_response() to output its final result, rather than output text directly.
2.5 When the set_model_response() is called, ADK will extract its content and put it in a text part, so the client would treat it as the model response.
PiperOrigin-RevId: 792686011
Xiang (Sean) ZhouandCopybara-Service