Back porting Dark theme bug fixes from R

Applying theme on start
update system properties on startup to apply the updates

Fixes: 149441632
Fixes: 149385662
Test: UiModeManager tests
Change-Id: I7f71e27a43eb24be833b3003340653fefc75d0cc
Merged-In: I0bee6517b39216146681097262cf55c7192b0131