title: RealityKit arview snapshot not capturing 3d object
body: <p>I currently have an application using RealityKit to add AR content to the view. I have a button that allows the user to take a photo. Based on the documentation, ARView.snapshot() seems to do this. However, the image captured is not including the AR content(3D object).</p>
  
  <pre><code>ARViewContainer().arview.snapshot(saveToHDR: false) { image in
      UIImageWriteToSavedPhotosAlbum(image!, nil, nil, nil)
  }
  </code></pre>
  
  <p>There is no error with this function but the captured snapshot is only a "camera photo" but no containing the AR Content(3D object) that is in the ARView.</p>