KeyguardLifecyclesDispatcher improvements

 - New @KeyguardLifecycleMessageType for type-safety

 - Fix HandlerLeak warning

 - Explicitly run KeyguardLifecyclesDispatcher's handler on the main
   looper

 - Improve keyguard lifecycle tracing by overriding getTraceName()

Test: SystemUITests
Bug: 193615254
Change-Id: Id281c20042fd999f8ecad44f8f002a5064663a8a
Merged-In: Id281c20042fd999f8ecad44f8f002a5064663a8a