Explicitly use Main thread context for a few view models

this fixes a few crashes related to the usage of the bg dispatcher for activating view models. Crashes were happening mainly when expanding dual shade.

Bug: 421000550
Test: expand/collapse dual shade + existing unit tests for changed classes
Flag: com.android.systemui.remember_view_model_off_main_thread
Change-Id: I3bbf16d67ec530fb19fc556c6edd7bfd433cef51