Core: Enable TaskDialogs to associate view (#17373)

* Core: Add possibility for task dialogs to associate a view and be able to close when associated view is closed.

* TaskImage: Use task dialog view association.

* Sketcher: Use task dialog view association. Preventing crash (https://github.com/FreeCAD/FreeCAD/issues/16702)

* EditableDatumLabel: Use QPointer to prevent crash

src/Gui/Application.cpp

@@ -1411,6 +1411,11 @@ void Application::viewActivated(MDIView* pcView)
     }
 }
 
+/// Gets called if a view gets closed
+void Application::viewClosed(MDIView* pcView)
+{
+    signalCloseView(pcView);
+}
 
 void Application::updateActive()
 {