🐛 [firebase_vertexai] Add response schema just like google_generative_ai

[imhafeez]

What feature would you like to see?

Is there a missing a feature that is supported on an underlying SDK? Or is there a feature that you think would be useful to have in FlutterFire?

In google_generative_ai you can control the output schema of your prompt. GenerationConfig.responseSchema but its missing in firebase_vertexai.

[MaggieThomann]

Yes please!! Big +1 to this. Seems like it would be simple enough to add.

[cynthiajoan]

Added in GA PR https://github.com/firebase/flutterfire/pull/13453