MediaSession2: Last changes before API unhide

This CL includes
- Rename SessionToken to SessionToken2
- Add repeat/shuffle mode support in PlaylistParam
- Add Executor params in session builder
- Add more APIs for MediaPlayerBase

Test: Run all MediaComponents tests once
Change-Id: Ia61632b7a09fab7f41fd89e9489a01af13d6c3c2
18 files changed