Update view model when desk organizer updates tasks.

When an onTaskInfoChanged event reaches DesksOrganizer, it does not ultimately reach DesktopModeWindowDecorViewModel, meaning window decorations end up with outdated taskInfo. This CL fixes this by calling view model's onTaskInfoChanged during RootTaskDesksOrganizer#onTaskInfoChanged

Bug: 404292560
Test: Manual, logging
Flag: com.android.window.flags.enable_multiple_desktops_backend
Change-Id: Iac6f0afdfe3c4aff871886a650fc0b142c72dd2d