Force SHOW_WALLPAPER flag when display switching

When unfolding from 'screen off' SHOW_WALLPAPER flag is not
set immediately on SystemUI side as dozing state/keyguard showing
state are updated asynchronously.

To ensure that the wallpaper is part of the unfold Shell
transition, at it is rendered in sync with the rest of
the windows before we turn on the inner screen, this change adds
forcing of SHOW_WALLPAPER flag for any display switching
transition.

Bug: 395612286
Flag: com.android.window.flags.ensure_wallpaper_drawn_on_display_switch
Test: atest NotificationShadeWindowControllerImplTest
Test: atest PendingDisplayChangeControllerTest
Change-Id: I24cf9faa7256e9ff7902fbd92358280118021f24