[1/2] Split the TaskView into View and Shell part.

- Details: go/splitting-taskview-one-pager
- TaskViewTaskController is the Shell part which has all the logic of the
  current TaskView.
- TaskViewBase is a stub used by the TaskViewTaskController that represents the
  SurfaceView.
- TaskView is now an implementation of TaskViewBase which uses the shell
  (TaskViewTaskController) directly.
- There can be other implementations of TaskViewBase that uses the shell
  (TaskViewTaskController) via binder.
- This split eventually enables us to provide build a remote
  implementation of TaskViewBase which doesn't depend on the Shell.

Fix: 265075065
Fix: 265951399
Test: atest TaskViewTest
Test: atest PanelTaskViewControllerTest
Test: atest ControlsUiControllerImplTest

Change-Id: I5f8ce24208cf48d9e9bdfa78fac61b2b8594ba1c