Add album art and colorize players in new layout

- Use album art as background of player
- Colorize players based on album art, or app icon if no art
- Use new icons for the default semantic actions (play/pause, prev, next)

Test: visual, with and without flag and art
Test: atest MediaControlPanelTest
Fixes: 209655797
Fixes: 209658115
Bug: 209657555

Change-Id: Ibeeeab89939dff07c8a9b8ae6aab2f339033e600