Re-map DisplayAreaAppearedInfo to token-leash map

Clean-up DA callback APIs of OneHandedDisplayAreaOrganizer
  onDisplayAreaAppeared()
  onDisplayAreaVanished()

Note:
  When super.unregisterOrganizer() is called, all DAs should be
  removed from the map in the callback of onDisplayAreaVanished().
  It was not working correctly because the map is using DisplayAreaInfo
  as the key, which will be different because of the different
  configuration object. We should use the DA token as the key.

Bug: b/172298357
Test: atest WMShellUnitTests:OneHandedDisplayAreaOrganizerTest
Test: atest SystemUITests
Test: Trigger OHM, rotate screen
Test: Trigger OHM, disabled through settings
Change-Id: I4560df1ab36ec33292fa4ec08cab28644b0fabe2