feat(vertexai): Add flutter_soloud for sound output in Live API audio streaming example.

[khanhnwin]

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[MichaelVerdon]

Hi there, thanks for the PR! I understand that this is a draft but can you please give me some more detail about this? I recently added a sound example to vertexai https://github.com/firebase/flutterfire/blob/main/packages/firebase_vertexai/firebase_vertexai/example/lib/pages/audio_page.dart unless yours is different?

[khanhnwin]

Hey @MichaelVerdon! From my understanding, the audio page that you linked to is for recording a it of audio and sending it to the Gemini API as opposed to streaming live audio, right?

I'm working with @cynthiajoan on refining the Live API example page, so in this case it's bidirectional audio streaming here => https://github.com/firebase/flutterfire/blob/main/packages/firebase_vertexai/firebase_vertexai/example/lib/pages/bidi_page.dart. Docs: https://firebase.google.com/docs/vertex-ai/live-api?platform=flutter

Edit: I realize my PR title was unclear, so I added more detail!