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.cpp

@@ -341,6 +341,12 @@ bool ICore::showWarningWithOptions(const QString &title, const QString &text,
     return false;
 }
 
+ bool ICore::isQtDesignStudio()
+{
+    QtcSettings *settings = Core::ICore::settings();
+    return settings->value("QML/Designer/StandAloneMode", false).toBool();
+}
+
 /*!
     Returns the application's main settings object.