feat(bar): hide when leaving komorebi's virtual desktop

This commit adds a new VirtualDesktopNotification which is used to
notify subscribers when the user leaves and enters the virtual desktop
associated with komorebi.

komorebi-bar consumes these notifications to minmize and restore the bar
appropriately depending on the currently focused virtual desktop.

re #1420

komorebi-bar/src/widgets/komorebi.rs

@@ -718,6 +718,7 @@ impl KomorebiNotificationState {
         let show_all_icons = render_config.borrow().show_all_icons;
 
         match notification.event {
+            NotificationEvent::VirtualDesktop(_) => {}
             NotificationEvent::WindowManager(_) => {}
             NotificationEvent::Monitor(_) => {}
             NotificationEvent::Socket(message) => match message {