Playback performance improvements

[naveensingh]

This PR resolves some of the problems mentioned in #604

Major changes:

• Only set mediaId on media items on the controller side and inflate as needed in the service
• Update media3 to 1.2.0-alpha02 (includes some fixes)
• Ensure we are loading media in a separate background thread instead of on the player thread.
• Implement lazy seek to next/previous media item behavior to avoid doing too much work on large playlists.
• Improve tracks recycler view when there are large items in the list

Related issues:

• Blocked UI when using large playlists androidx/media#81 (once resolved, this should solve most performance-related issues)
• Blocking main thread when set media items androidx/media#592
• Blocking main thread when set media items androidx/media#592

Tested playing ~4-5k items on a queue on a device with average specs and it worked pretty well. Large playlists kept getting slower and slower, 10k items are still not usable on below-average devices.

[tibbi]

should be good, will do more testing in the real app. Thanks