Utils: Make the second parameter to LayoutBuilder::attach() an enum

More explicit and more potential options (e.g. "treat grid as form")
than a bool.

Change-Id: I89413efe30410160c38b0e524ba64288dde2332e
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/fakevim/fakevimplugin.cpp

@@ -450,7 +450,7 @@ void FakeVimOptionPage::layoutPage(QWidget *widget)
         Row { copyTextEditorSettings, setQtStyle, setPlainStyle, st },
         st
 
-    }.attachTo(widget, true);
+    }.attachTo(widget);
 
     s.vimRcPath.setEnabler(&s.readVimRc);