Prefer launching desktop tasks on freeform display

Update usages of TaskbarActivityContext.inDesktopMode to account for a
possibility of a desktop flavour taskbar (i.e. pinned taskbar that
shows desktop tasks) being shown outside desktop mode, which may be the
case on freeform displays (e.g. when
enable_desktop_taskbar_on_freeform_displays feature is enabled, or on
home). Tasks launched from this taskbar should preferably be launched
into desktop mode.

Bug: 390665752
Flag: com.android.window.flags.enable_desktop_taskbar_on_freeform_displays
Test: manual on desktop device. verify correct taskbar is shown
      on home screen, in overview, in desktop mode, with fullscreen
      app shown. Verify opening/launching apps from taskbar works
      as expected.

Change-Id: I8f198216d84fd165c2dcbf437c82e418e5c7405e

quickstep/src/com/android/launcher3/taskbar/BaseTaskbarContext.java

@@ -57,10 +57,17 @@ public abstract class BaseTaskbarContext extends BaseContext
     public abstract NavigationMode getNavigationMode();
 
     /**
-     * Returns whether the taskbar is in desktop mode.
+     * Returns whether the taskbar is in desktop mode. Implies that some desktop tasks are currently
+     * visible.
      */
     public abstract boolean isInDesktopMode();
 
+    /**
+     * Returns whether the taskbar is showing desktop tasks, which may happen even outside desktop
+     * mode on freeform displays.
+     */
+    public abstract boolean isTaskbarShowingDesktopTasks();
+
     /**
      * Returns whether the taskbar is forced to be pinned when home is visible.
      */