Prevent activities on rear display

1) Add concurrent state to DeviceStateController

2) Updated ActivityTaskSupervisor to prevent activities on rear
   display

3) Exposes DisplayManager.DISPLAY_CATEGORY_REAR as TestApi so that we
   can use it in CTS. Updates existing test to check that there is
   at least one rear display when concurrent mode starts.

4) Adds CTS that enforces activities cannot be launched on the
   rear display

Fixes: 267218677

Test: atest DeviceStateControllerTests
Test: atest android.server.wm.jetpack.ExtensionRearDisplayPresentationTest#testStartActivityOnRearDisplay_whileRearPresentationSessionStarted

Change-Id: I93411c892ed53e8f46980497f4189de1fa5fbec3