Add KeyguardStatusViewController

Refactor KeyguardStatusView so that it has a controller that
NotificationPanelViewController can use to manipulate the view. This
CL untangles some of the logic in KeyguardStatusView that should be in
KeyguardClockSwitchController.

No functionality changes.

Test: atest KeyguardClockSwitchControllerTest
Test: atest NotificationPanelViewTest
Test: atest KeyguardStatusViewControllerTest
Test: atest SystemUITests
Change-Id: I52d0d887cb4ce734ec265b6357644ba1d1368460
Bug: 170228350