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/texteditor/behaviorsettingswidget.cpp

@@ -257,7 +257,7 @@ BehaviorSettingsWidget::BehaviorSettingsWidget(QWidget *parent)
     Row {
         Column { d->tabPreferencesWidget, d->groupBoxTyping, st },
         Column { d->groupBoxStorageSettings, d->groupBoxEncodings, d->groupBoxMouse, st }
-    }.attachTo(this, false);
+    }.attachTo(this, WithoutMargins);
 
     connect(d->cleanWhitespace, &QCheckBox::toggled,
             d->inEntireDocument, &QCheckBox::setEnabled);