wip/runtime2: Scene window doesn't render scene accurately when presentation size is larger than editor main window size

wip/runtime2:

Scene window doesn't render scene accurately when presentation size is larger than editor main window size. The geometry of actual OS level subwindow used as the surface is likely limited by parent window geometry, causing the incorrect rendering. E.g. set presentation height to 1000 and gradually resize the editor window height smaller -> the objects in the scene will stretch after the presentation height exceeds the main window height.

If the presentation size is larger than the logical screen resolution, scene view can start flickering or exhibit other kinds of weird behaviors.

It is likely that we need to render to QOffscreenSurface rather than QWindow, meaning we should use QOpenGLWidget like the old implementation did.