Window blur during hub and edit mode transition

This change introduces a new transition view model for the glanceable
hub and edit mode transition. Because the window blur is covered by a
background that SystemUI applies during the transitions, it only needs
to snap to the correct value according to the current edit mode state.

Test: atest GlanceableHubToEditModeTransitionViewModelTest
Bug: 419361764
Flag: com.android.systemui.hub_edit_mode_transition
Change-Id: I505d36b0d673614ce063278d638d39956b8ad4f0