Support for response schema in FunctionDeclaration to enable Async (Non-Blocking) Function Calling.

## What feature would you like to see?

I would like the FunctionDeclaration class in the Android SDK (Firebase AI / Vertex AI) to accept a response parameter of type Schema. This field is currently missing but is required by the Gemini Live API to enable "Client-side async tools" (also known as NON_BLOCKING mode).

## How would you use it?

I am building a real-time voice application using the Gemini Live API. I have tools (functions) that take time to execute (e.g., fetching weather, looking up database records), but I do not want the model's audio generation to pause while these tools run.

According to the Gemini API documentation for Async Function Calling, providing a response schema in the function declaration allows the model to predict the tool's output structure and continue the conversation immediately without waiting for the actual execution result.

Start by locating the FunctionDeclaration class in the Android SDK and review how its existing parameters are represented. Check the Gemini Live API documentation for the response Schema requirement and inspect related tests if present. Done means FunctionDeclaration accepts the requested response schema for client-side async tools without breaking existing declarations.

Written by the indexing model from the issue text.