How to add the visualization.O3DVisualizer component to a PySide window?

### Checklist

- [x] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [x] For Python issues, I have tested with the [latest development wheel](https://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [x] I have checked the [release documentation](https://www.open3d.org/docs/release/) and the [latest documentation](https://www.open3d.org/docs/latest/) (for `main` branch).

### My Question

I am developing an integrated application based on PySide6, and I need to display some point cloud information with text labels. The old Visualizer cannot directly add labels, and I cannot find a way to integration the new O3DVisualizer.
So I'm asking for a sample to integration the O3DVisualizer.