Be able to use multiple QQuickRenderControls for a QOpenGLContext

For performance reasons it is desired to reuse the QOpenGLContext of a QOpenGLWindow to do the rendering of a QQuickRenderControl. This works perfectly fine as long as you have one QQuickRenderControl. However, if there is a need to be have multiple QQuickRenderControls then this is not possible because each QOpenGLContext has exactly one QSG_RENDERCONTEXT_PROPERTY property which the QQuickRenderControl uses.

It would be good if this could be made possible so it is possible to specify a different QQuickRenderControl to be used if desired.