Move accessibility gesture code into its own package.

Given the number of classes that are going  to be created (gesture detectors, TouchExplorer state handlers) it made sense to put them into their own package.
Bug: 136131815
Test: atest CtsAccessibilityServiceTestCases CtsAccessibilityTestCases

Change-Id: Ie347424ecd7518a7c5a4fdefdca5b4886b1fd8e4
12 files changed