Refactor brightness stack

This refactored stack provides a view model and a Compose UI that can be
easily reused.

Also, add a new ViewModel for the new QS UI. Different items in QS
should have view models added to it.

Missing:
* Metric events
* Logs
* Actual UI

Flag: ACONFIG com.android.systemui.qs_ui_refactor DEVELOPMENT
Fixes: 330357906
Test: atest com.android.systemui.brightness
Test: manual (using test activity)

Change-Id: Ib2e453ed10fb01e890557fabec91dba6ec96bf04