Add the "collapse" and "open" functions to TreeView in python

### 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).

### Proposed new feature or change

When adding many items to the TreeView (with different hierarchies) the widget get crowded very quickly. It's possible to collapse and open a single parent item from the interface with the mouse, but I could not find a way to do it from code.

I would like to have the option to collapse and open them via code.

### References

_No response_

### Additional information

_No response_