Ensure that TaskView callbacks are made on the ui thread for the view

- In cases where the TaskView are not created on the shell main thread,
  the callbacks on the view may be made on the wrong thread leading to
  an error or the a race between usage/cleanup of the surfaces used by
  the surface view.

Fixes: 292241747
Fixes: 300870297

Test: atest TaskViewTest
Test: atest PanelTaskViewControllerTest
Test: atest ControlsUiControllerImplTest
Change-Id: I43bbd9d8089d0ab6e6bd10dd5cb4072f0029d8dc