Request to add support for 2D plotting libraries?

### 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](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### Proposed new feature or change

Hi, does open3D's GUI framework support integration with 2D plotting libraries such as `matplotlib.backends.backend_qt5agg`, which can be easily embedded in PyQt GUIs? I think this capability would make Open3D GUI even more powerful. Thank you.

### References

_No response_

### Additional information

_No response_