Changing the interaction model of the touch explorer.

1. Now the user have to double tap to activate the last
   item. If the last touched window is not active because
   it does not take input focus the click on the last
   touch explored location. Othewise the click is on the
   accessibility focus location.

bug:5932640

Change-Id: Ibb7b97262a7c5f2f94abef429e02790fdc91a8dd