Adding some more gestures and actions for accessibility.

1. Added more gesture for accessibility. After a meeting
   with the access-eng team we have decided that the current
   set of gestures may be smaller than needed considering
   that we will use four gestures for home, back, recents,
   and notifications.

2. Adding actions for going back, home, opening the recents,
   and opening the notifications.

3. Added preliminary mapping from some of the new gestures
   to the new actions.

4. Fixed a bug in the accessibility interaction controller
   which was trying to create a handled on the main looper
   thread which may be null if the queried UI is in the
   system process. Now the context looper of the root view
   is used.

5. Fixed a bug of using an incorrect constant.

6. Added a missing locking in a couple of places.

7. Fixed view comparison for accessibilityt since it was
   not anisymmetric.

bug:5932640
bug:5605641

Change-Id: Icc983bf4eafefa42b65920b3782ed8a25518e94f