Add buttonless UI for watch type devices.

Watch type devices defaults to using an interaction model that
  avoids the use of buttons in AlertDialogs. A buttonless
  mode was added and enabled for watch devices to conform
  with the behaviour of other similar dialogs.

Test: manual using watch system settings

Bug: 30946435
Change-Id: Iaee39ac373bc5c1ec669cdaea025a56360725f28
3 files changed