Move Platform::createMainWindow() to dev mode

This is for tests only

src/qtquick/TestHelpers_qtquick.cpp

@@ -12,6 +12,8 @@
 #include "KDDockWidgets.h"
 #include "Platform_qtquick.h"
 #include "views/View_qtquick.h"
+#include "qtquick/views/MainWindow_qtquick.h"
+#include "controllers/MainWindow.h"
 
 #include <QApplication> // TODO: Make it QGuiApplication
 #include <QQmlEngine>
@@ -101,4 +103,31 @@ View *Platform_qtquick::tests_createNonClosableView(View *parent)
     return nullptr;
 }
 
+Controllers::MainWindow *Platform_qtquick::createMainWindow(const QString &uniqueName,
+                                                            CreateViewOptions viewOpts,
+                                                            MainWindowOptions options,
+                                                            View *parent, Qt::WindowFlags flags) const
+{
+    QQuickItem *parentItem = Views::asQQuickItem(parent);
+
+    if (!parentItem) {
+        auto view = new QQuickView(m_qmlEngine, nullptr);
+        view->resize(viewOpts.size);
+
+        view->setResizeMode(QQuickView::SizeRootObjectToView);
+        view->setSource(QUrl(QStringLiteral("qrc:/main.qml")));
+
+        if (viewOpts.isVisible)
+            view->show();
+
+        parentItem = view->rootObject();
+        Platform::instance()->tests_wait(100); // the root object gets sized delayed
+    }
+
+    auto view = new Views::MainWindow_qtquick(uniqueName, options,
+                                              parentItem, flags);
+
+    return view->mainWindow();
+}
+
 #endif