IMS-VT: FR36492 - UI to disable picture in picture mode

- Allow user to disable picture in picture mode if the adb
  property - "persist.disable.pip.mode" is set to 1

- Provide an alert dialog to the user on long press on the
  video call screen (incoming or far end) which shows options
  for camera preview and incoming picture modes

- If both options are selected, enable pip mode, if camera
  preview is selected, enable camera preview mode otherwise
  enable incoming video mode

- User can provide a size for the camera preview window for
  non-PIP camera preview mode through adb property -
  "persist.camera.preview.size" [format - widthxheight]

Change-Id: I49cb59e80914259b1a07cb63cd6965b5aff4f497
CRs-Fixed: 1054181