Introduce PrivacyDotViewControllerStore for multiple displays

+ Adds "stop" method so that the controller can unregister listeners

Test: Tested by parent abstract class
Test: Build & run
Flag: com.android.systemui.status_bar_connected_displays
Bug: 362720432
Change-Id: I20fbf998432a1745d59ed1f36a5a2e02e4ebdebd