SDK / exoplayer

* Add a new event `onAudioCapabilitiesChanged` in `AudioSink.Listener` interface.
* Add an interface `RendererCapabilities.Listener`, which will listen to `onRendererCapabilitiesChanged` events from the renderer.
* Add `getRendererCapabilitiesReceiver` method for `TrackSelector`, and register/unregister the `TrackSelector` as the `RendererCapabilitiesReceiver` (if implemented) when the `ExoPlayer` is initialized/released.
* Trigger the `AudioSink.Listener.onAudioCapabilitiesChanged` and further `RendererCapabilities.Listener.onRendererCapabilitiesChanged` events when the audio capabilities changes are detected in `DefaultAudioSink`.

PiperOrigin-RevId: 521427567