QmlDesigner: Fix zoom to current selection

Fix zoom screen to current selection by adding the active manipulator
layer items bounding box to the bounding box dictating the zoom.

Task-number: QDS-15273
Change-Id: I33ab0eb09af2b7fa3a2a61788681c2558ab0a63d
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/components/formeditor/formeditorwidget.cpp

@@ -236,6 +236,7 @@ FormEditorWidget::FormEditorWidget(FormEditorView *view)
                 if (FormEditorItem *item = m_formEditorView->scene()->itemForQmlItemNode(node))
                     boundingRect |= item->sceneBoundingRect();
             }
+            boundingRect |= m_formEditorView->scene()->manipulatorLayerItem()->boundingRect();
             m_graphicsView->frame(boundingRect);
             zoomOut();
         }