Reduce usages of ContextThemeWrapper causing memory churn

- Cache light/dark icon colors so we don't have to create additional
  theme wrappers when updating them
- Convert rotation styles to separate drawables so we can skip creating
  theme wrappers just to change some attributes of the drawable, these
  icons are not changed much so it's worth the memory savings even if
  this introduces copies of the drawable
- Clean up floating rotation drawable initialization slightly, only create
  when updating the icon, and only start the animation when showing the
  drawable
- Removed some unused code

Bug: 157510126
Test: atest SystemUiTests
Test: Verify rotation icon looks the same in all orientations with both
      three button and gestural, and also with light/dark nav bar

Signed-off-by: Winson Chung <winsonc@google.com>
Change-Id: I31e89f7aef00b38f2a7953d6e229c9ed7df8b479