Initial sleep-lock-screen implementation

We're now listening for sleep events and forcing the device into
sleep mode when necessary.

Display state is now cached and handled properly for cases where
the device wakes up and should go back to sleep.

Test: atest LockScreenWakeUpControllerTest
Test: manual
Bug: 111414690
Bug: 111405682
Fixes: 120864496
Change-Id: I3096329e8f6a07a686582d35c4b0e9977bf9ab1b