Adding accessibility support to the tablet swipe unlock.

1. Added handling for hover events that are transformed into
   touch events and given to the touch event handling code
   if accessibility is enabled.

2. Now swiping across the handle unlocks the device for both
   cases - accessibility enabled or disabled.

bug:5513324

Change-Id: I7031690d69b1a2737e2ce4d1871d69d7dfbf3006