[feat] add support for Gemini Live from firebase_ai

[csells]

Check out this docs issue: firebase/flutterfire#17413

Check out this sample: https://github.com/firebase/flutterfire/blob/main/packages/firebase_ai/firebase_ai/example/lib/pages/bidi_page.dart

[mit-mit]

tentatively moving to 1.0

[csells]

Can you say more about how live would work with the AI Toolkit inside a chat widget context?