Force show system bars while menus are open in desktop immersive

Keeps the bars showing while the Handle Menu or Manage Windows menus are
open, and adjusts their position on screen to account for App Header
padding.

This requires changing these windows to use
AdditionalSystemViewContainer because setting forciblyShownTypes on
windowless windows has no effect on the system bars' visibility.

Flag: com.android.window.flags.enable_fully_immersive_in_desktop
Bug: 372319957
Test: enter desktop immersive with YT on Chrome, check menus force-show
the system bars and they're anchored to the App Chip instead of the top
of the screen/task.

Change-Id: I2cfd7b416c66ed89d2e2556d644c01bcab846dcd