DesktopTasksController: Let Wallpaper launchable on ext. displays.

By default right now the wallpaper is only launched on default display,
even if desktop mode is entered on a non-default display. Pass in a
displayId so that it can be launched on other displays.

Bug: 382023296
Test: Manual. Start Desktop Mode on ext display and see that Wallpaper
is launched along on the secondary display.
Flag: com.android.window.flags.enable_bug_fixes_for_secondary_display

Change-Id: I3e1f1342b8c5ef65a8fc9e7b711240684e5692d3