Fix jank when switching themes

Turning overlays on and off takes time,
it also doesn't allow us to have fine control
over which view is using which theme.
Lock screen colors are now driven by themes.

Change-Id: Ie8860d00dbb0705ed76edf60a9d3030618dd21ca
Fixes: 63751714
Test: Visual. Set wallpapers, unlock.
Test: runtest -x packages/SystemUI/tests/src/com/android/keyguard/KeyguardSecurityContainerTest.java
Test: runtest -x tests/Internal/src/com/android/internal/colorextraction/ColorExtractorTest.java
Test: systrace