Desks: Incompatible Tasks (2/2) - Adjust launch WCT for desks

Makes a couple of adjustments to the WCT in
handleIncompatibleTaskLaunch() when multiple-desks is enabled:
1) to-transparent-fullscren task tracking isn't needed - instead, when
   one of these tasks launches, the desk is kept in an active state.
2) Even if the task is already fullscreen, ensure
   addMoveToFullscreenChanges runs, so the task is reparented to the TDA
   and the desktop state is cleaned up
3) Set |forceExitDesktop| to true|false based on task transparency:
   opaque tasks always force-exit the desktop, transparent tasks always
   keep the desktop active.

Flag: com.android.window.flags.enable_multiple_desktops_backend
Bug: 398295550
Test: while in desktop, launch incompatible tasks and check opaque ones
go fullscreen and exit the desktop, while transparent ones go fullscreen
but keep the desktop active.

Change-Id: I720a6477511fcafa8e914f5703d57e43e1f1c4e8