AllApps tray icon tap: use showDesktopApp() for existing Desktop tasks

When tapping an icon in the AllApps tray, before this CL, we would use
the WM Shell API startLaunchIntentTransition() to launch a task for that
app icon. However, this would break the window limit logic since in WM
Shell (startLaunchIntentTransition()) we think we're launching a new
task, when in fact we're just moving an existing one to the front.
With this CL we instead reuse the showDesktopApp() API whenever the app
we're trying to launch has an already visible / minimized Desktop task.

Bug: 391365151
Test: launch visible Desktop app from AllApps - doesn't overtrigger
window limit
Flag: com.android.window.flags.enable_desktop_app_launch_transitions_bugfix

Change-Id: Ia3638012226fe28c853ec6cfd0523a8fb23b8961
3 files changed