MediaPlayerBase: Add PlayerEventCallback#onSeekCompleted()

PlayerEventCallback#onSeekCompleted() will be called when the
MediaPlayerBase#seekTo() is completed. Following callbacks are also
added to listen the event.
  - SessionCallback#onSeekCompleted()
  - ControllerCallback#onSeekCompleted()

Bug: 74370608
Test: Build
Change-Id: Ib1ecd75f7e217ed9a927db3ab443073a1aef2074
3 files changed