Fix failing accessibility CTS tests.

1. If the device is too aggressive in conserving power it is possible
   that by the time we start running some accessibility tests the
   screen had already timed out. Now we are setting special window flags
   for the accessibility test activities to turn the screen on and
   keep it on until this activity is on the screen.

2. On very slow devices the timeout for detecting when accessibility
   events are settled was not enough.

3. The accessibility text edit actions are not relevant to devices
   that have no input method feature. Hence, the test for edit actions
   is ignored on such devices.

4. The window traversal test was relying on a specific decor view
   but an OEM can change the decor causing the test to fail.

5. Removed some unused code.

bug:15027113
bug:15028454
bug:15003040
bug:15006113
bug:14901134
bug:14901768

Change-Id: Ibf10d8d5413fdf95c7105d3ea1cd1abd9ddaec1b