Core: add ICore::isQtDesignStudio()

Change-Id: I3aed97b62abd05b283ac327be210af75f173383d
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/coreplugin/icore.h

@@ -68,6 +68,7 @@ public:
                                        Utils::Id settingsId = {},
                                        QWidget *parent = nullptr);
 
+    static bool isQtDesignStudio();
     static Utils::QtcSettings *settings(QSettings::Scope scope = QSettings::UserScope);
     static SettingsDatabase *settingsDatabase();
     static QPrinter *printer();