Add HANDLE_CAR_MODE_CHANGED permission

Required to allow DeviceStateMonitor to monitor changes in car mode to
get an accurate state of when all screens are on/off.

Test: build
Bug: 160898432
Change-Id: If3ad86a2564ce3ba53afea44e8ad5bf02b8d51e0
Merged-In: If3ad86a2564ce3ba53afea44e8ad5bf02b8d51e0