Let wallpaper colors drive system theme

Refarctored ThemeOverlayManager and ThemeOverlayController to conform to
current SysUI paradigm (dependency injection) and registered
WallpaperManager listener so themes can be driven by system colors.

Test: manual
Test: atest ThemeOverlayControllerTest
Test: atest ThemeOverlayApplierTest
Bug: 171916625
Change-Id: Icbc1e0f6bcda160b4ba9dd39fe29938bce538689