Media notification updates

- Make text white.
- Adjust padding & metrics to redlines.
- Use different narrow layout when 3 or less notifications with big
  picture.
- Update action ripples.
- Fix progress bar size & fix color for indeterminate progress bar.
- Apply default background in SystemUI when no color is set, so we
  don't end up with white text on white background.

Bug: 15437369
Bug: 16625746
Bug: 15147533
Change-Id: Ie8bd5ad0bbca972685adb50034fff88ea97456bd