Add bug fix flag for maximized/tiled scrim

This is a bug fix flag to add a scrim to wallpaper when a desktop window
is get to maximized, or windows get to tiled states.

Bug: 406869685
Test: build
Flag: com.android.window.flags.dimming_wallpaper_for_maximized_and_tiled
Change-Id: I335b2783cb8a2105efcdca502f945e7b48c7dc64