Refactor ProjectedContextActivity and MainActivity

- Refactored MainActivity with status bar padding and test launcher.
- Refactored ProjectedContextActivity to isolated Controller and ViewModel.
- Upgraded ProjectedActivity UI on projected display to high contrast.
- Scoped projected activity lifecycle to terminate when phone activity
  finishes.
- Configured AndroidManifest.xml with taskAffinity and wake flags.

Test: ./gradlew :xr:projected:integration-tests:testapp:lintDebug
Test: ./gradlew :xr:projected:integration-tests:testapp:assembleDebug
Relnote: N/A
Change-Id: Id669813ba45cc2210c9ea6d2e454049fac741ba3