Rename some shellclients methods, maybe squash some parts of this

Author: leolost2605

src/ShellClients/PanelWindow.vala

@@ -88,6 +88,11 @@ public class Gala.PanelWindow : ShellWindow, RootTarget {
         update_strut ();
     }
 
+    public void request_visible_in_multitasking_view () {
+        visible_in_multitasking_view = true;
+        actor.add_action (new DragDropAction (DESTINATION, "multitaskingview-window"));
+    }
+
     private void hide () {
         gesture_controller.goto (1);
     }

src/ShellClients/ShellClientsManager.vala

@@ -191,7 +191,7 @@ public class Gala.ShellClientsManager : Object, GestureTarget {
             return;
         }
 
-        panel_windows[window].visible_in_multitasking_view = true;
+        panel_windows[window].request_visible_in_multitasking_view ();
     }
 
     public void make_centered (Meta.Window window) requires (!is_itself_positioned (window)) {