Add an example of how to use the multisplitter with QtQuick

src/private/multisplitter/Widget_qwidget.h

@@ -60,6 +60,9 @@ public:
     void show() override;
     void hide() override;
     void move(int x, int y) override;
+    void setSize(int width, int height) override;
+    void setWidth(int width) override;
+    void setHeight(int height) override;
 
     static QSize widgetMinSize(const QWidget *w);