Dual target modes tile

The secondary tap target can now toggle DND directly.

Updated ZenModeInteractor#dndMode to make it a StateFlow, so we can
reuse it both here and for the DND quick affordance.

Bug: 380908293
Test: ModesTileUserActionInteractorTest
Test: manually test that the toggle works
Flag: android.app.modes_ui
Flag: com.android.systemui.qs_ui_refactor_compose_fragment

Change-Id: I8f608203eb9f39da2fe2928362a629292e5a01d9