appops: Respect screen interactivity before creating dialogs.

  If the device's screen is currently off, do not queue ask
  runnables who cannot be interacted with. Since these events
  are gating mechanisms for closing an IPC loop, they need to
  happen when the user is interacting with the device.

  Likewise, on screen off, clear the queue of every op as they
  become unnecessary.

Change-Id: Ie930d200839c9408e882510c6bc3ede37ea889ef
TICKET: CYNGNOS-2869
(cherry picked from commit 1c1efe46)