2/ Migrate isInOneHanded() in OneHandedState

It's make sense to let controller manage function states,
and left organizer handle leash & transition stuffs.

Move isInOneHanded() in OneHandedState.java

Controller can get STATEs throught organizer callback:
 - onTransition()
 - onStartFinish()
 - onStopFinsih()

Test: atest WMShellUnitTests
Bug: 185558765
Change-Id: I741b191557ed8e8ca85184d75a7bd8a2573e9b7c