QmlDesignerBase: Remove the dependency on IOptionPage's QObject base

The base will be cut soonish, and the only use here was tr() with
a (wrong) context. Use StudioSettingsPage for that now.

Change-Id: I41e4b737713591e002c126bbf97226de7c3f784f
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

src/plugins/qmldesignerbase/qmldesignerbaseplugin.cpp

@@ -264,7 +264,7 @@ void StudioSettingsPage::apply()
 StudioConfigSettingsPage::StudioConfigSettingsPage()
 {
     setId("Z.StudioConfig.Settings");
-    setDisplayName(tr("Qt Design Studio Configuration"));
+    setDisplayName(StudioSettingsPage::tr("Qt Design Studio Configuration"));
     setCategory(Core::Constants::SETTINGS_CATEGORY_CORE);
     setWidgetCreator([] { return new StudioSettingsPage; });
 }

src/plugins/qmldesignerbase/qmldesignerbaseplugin.h

@@ -35,8 +35,6 @@ private:
 
 class QMLDESIGNERBASE_EXPORT StudioConfigSettingsPage : public Core::IOptionsPage
 {
-    Q_OBJECT
-
 public:
     StudioConfigSettingsPage();
 };