Style priority modes items in aggregator

* Different color if active.
* Trigger description / "ON" / "Paused" / "Tap to set up" depending on enabled and active status (strings may be revised later).

This CL also adds a helper class to create ZenModes, reducing boilerplate in unit tests.

Bug: 346575288
Test: atest com.android.settings.notification.modes
Flag: android.app.modes_ui
Change-Id: Ia0e16b8be5284d13bed4366cbee0f92748bf2f85