Use State in ViewModel instead of StateFlow

This simplifies a lot of the code and aligns with recommended
architecture.

Also, wire up isSplitShade

Test: atest com.android.systemui.qs.composefragment.viewmodel
Bug: 353253277
Flag: com.android.systemui.qs_ui_refactor_compose_fragment
Change-Id: Ic0c581a06d785153e741acc392041c311b2185a7
5 files changed