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/MDIView.cpp

@@ -209,6 +209,8 @@ void MDIView::closeEvent(QCloseEvent *e)
 {
     if (canClose()) {
         e->accept();
+        Application::Instance->viewClosed(this);
+
         if (!bIsPassive) {
             // must be detached so that the last view can get asked
             Document* doc = this->getGuiDocument();