[flexiglass] Separates smartspace view from view-model

This is a necessary step for integrating the views within
keyguard/ui/view/layout/sections/SmartspaceSection.kt into the new
keyguard/ui/composable/section/SmartSpaceSection.kt: namely, the removal
of the incorrectly referenced views from KeyguardSmartspaceViewModel (in
MVVM, view-models mustn't refer to views anyway).

Bug: 316211368
Test: manually verified that the lockscreen smartspace looks correct in
the old KeyguardRootView implementation outside of Flexiglass
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT

Change-Id: I9408397c1418b07498a42abfc722bab3d72be964