feat(EDT): Sync force invert callback register by IfThisThenThat Lint

Add labeled blocks to both UiModeManagerService and ViewRootImpl to
clearly mark the code sections responsible for registering the ContentObserver.

Bug: 368721320
Flag: android.view.accessibility.force_invert_color
Test: manual testing
Change-Id: I13c8c42a3094a17cc0d4e189757eb35562e7abc9