[2/2] Split the taskview into view and shell part

- Move all the taskview related classes inside a new taskview
  sub-package.

Fix: 265075065
Test: atest TaskViewTest
Test: atest PanelTaskViewControllerTest
Test: atest ControlsUiControllerImplTest
Change-Id: I3c38a3b7512921484b9cbcbaac3602367b7df4cd