SDK / exoplayer

This provides an (unstable) API for apps to broadcast session extras
Bundle to all connected controllers and set the extras in the legacy
session.

Similar to the custom layout, the extras Bundle is not part of the
Media3 session state. This means that when a Media3 controller
connects to the session after the broadcast, the extras needs to be
sent to that controller in  `MediaSession.Callback.onPostConnect(MediaSession session, ControllerInfo controller)`.

PiperOrigin-RevId: 451871731