SDK / exoplayer

This is the first commit out of two. This change adds the missing event
flags for the onEvents() callback when MediaController is connected to a
media3 session (see MediaControllerImplBase). I updated the
MediaControllerListenerTest and MediaControllerStateMaskingTest with
assertions that on onEvents() is called alongside individual
Player.Listener callbacks.

There will be a follow-up change for the case where a MediaController is
connected to a legacy MediaSession (MediaControllerImplLegacy). I've
split this in two separate changes to make the size of the commit
manageable for reviewing.

#minor-release

PiperOrigin-RevId: 481933437