Redesigns the volume panel!

Demo video, since building is hard: https://drive.google.com/file/d/17lKjpHW0UGfHx7O9SPGb4VKxhRw1Vm87/view?usp=sharing

This is mostly cosmetic changes, other than the addition of the ringer drawer functionality.

TV uses the same controller but different layout files, which is why we do some null-checks to see whether the old ringer/icons are present.

Bug: 171441100
Test: atest SystemUITests
Test: manual
Change-Id: Id561cff010483b69d71ea9b48e7d17b500272073