Move home to front when bringing apps to front

- When `desktopWallpaperActivity` flag is enabled, we were not moving
  home to front before bringing desktop activities to front. It resulted
  in navigating to the previous fullscreen app, when all the windows
  were closed.
- Added `moveHomeToFront` event, when the flag is on, to ensure that
  home is in the beginning of the navigation stack so we always show
  home when we leave desktop.

Bug: 352326674
Test: atest WMShellUnitTests:DesktopTasksControllerTest
Flag: com.android.window.flags.enable_desktop_windowing_wallpaper_activity
Change-Id: I9f1b07ddfa605701d72a25185c626b2b8828d412