Ensure AlarmManager knows of IDLE state.

AlarmManager relies on AlarmManager.setIdleUntil to know when the device
is entering the IDLE state. Devices that want to use a motion sensor
but don't have one normally won't proceed to the IDLE state, but someone
could force the device into the IDLE state via adb. In that situation,
AlarmManager should still be told that the device entered the IDLE
state. The alarm scheduling method expects mState to be updated before
its called, so if the method is called before the state is updated, it
will do the wrong thing.

Bug: 270672228
Test: atest DeviceIdleTest
Test: atest FrameworksMockingServicesTests:DeviceIdleControllerTest
Change-Id: I95a06e37f218bfebc86ffa6a984b50b60013af7d