1/ Add OneHandedState to manage the transition flow

1) Define STATEs flags for OHM CUJ:
    STATE_NONE               (0)
    STATE_ENTERING           (1)
    STATE_ACTIVE             (2)
    STATE_EXITING            (3)

STATE_NONE->STATE_ENTERING->STATE_ACTIVE->STATE_EXITING

- Default = STATE_NONE
- When user trigger OHM        = STATE_ENTERING
- When user is in OHM          = STATE_ACTIVE
- When user exit OHM           = STATE_EXITING
- When user finish exiting OHM = STATE_NONE

2) Unbound one handed mode state from OHMDAOrganzier
- Move isInOneHandedMode() to OneHandedState

Test: atest OneHandedStateTest
Test: atest WMShellUnitTests
Test: manual test
Bug: 185558765
Change-Id: Ida2f23da6c4df9cbcf6903ffc9ad07fcfc73bbcb