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/projectexplorer/codestylesettingspropertiespage.cpp

@@ -72,7 +72,7 @@ CodeStyleSettingsWidget::CodeStyleSettingsWidget(Project *project)
     Column {
         Row { new QLabel(tr("Language:")), languageComboBox, st },
         stackedWidget
-    }.attachTo(this, false);
+    }.attachTo(this, WithoutMargins);
 }
 
 } // ProjectExplorer::Internal