* Add `BitmapLoader` in `MediaSession.Builder` and `MediaLibrarySession.Builder`.
* Pass `BitmapLoader` into the constructor of `MediaSession`, `MediaSessionImpl`, `MediaLibrarySession` and `MediaLibrarySessionImpl`.
* Add an interface method `loadBitmapFromMetadata(MediaMetadata)` in `BitmapLoader`.
* Remove the reference of `BitmapLoader` in `DefaultMediaNotificationProvider`.
PiperOrigin-RevId: 483654596
(cherry picked from commit 3f69df72)
