[feature] Add Javascript SDK`s createAudioAnalyser function

[dganzella]

Is your feature request related to a problem? Please describe.

Yes. We need to know when someone is talking while muted, a pretty common feature of all reliable modern telecom systems.

Describe the solution you'd like

Seems Livekit JS SDK already has this feature: https://docs.livekit.io/reference/client-sdk-js/functions/createAudioAnalyser.html

I`d like it available in the flutter SDK as well.

Describe alternatives you've considered

I tried checking the microphone levels for the current events, but the microphone level always goes to 0 when its muted.

Additional context

BuildContext context;