Merge changes from topic "subs" into p9.0
* changes:
OMS: handle target or overlay package disabled
OMS: try harder not to update assets if nothing changed
SubstratumService: Rewrite installation method for Pie InstallSession API
Unbreak public api by hiding substratum interfaces
Pie OMS: allow non-system overlays from Substratum
SubstratumService: Refactor & cleanup according to AOSP conventions
base: modify/define custom overlay management
SubstratumService: unify permissions
SubstratumService: allow CHANGE_OVERLAY_PACKAGES permission
base: Introduce SubstratumService
OMS: StrictMode and files under /data/system/theme/
Hold "volume up" during boot to disable all overlays
ThemeSafety: Introduce App Crash Intent
ApplicationsState: add filter for Substratum overlays [2/2]