How to use VisualizerWithEditing to show a mesh with its wireframe, and then add a callback to remove selected triangles?

### 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 have a concave triangulated mesh that I want to manually clean up, meaning that I want to select which triangles from the triangulation should be removed from the final result (as I couldn't get good results with alpha shapes).

I want to do the following:

Step A: Triangulation
1. Get the triangulation done with Delauney triangulation.
2. Draw the resulting mesh with `VisualizerWithEditing` showing the wireframe of the mesh.

Step B: First cleanup
1. Use the circumradius of the triangles for a first step cleanup (delete all triangules above a `max_accepted_radius`)
2. Use a callback to update the plot on the visualizer for different levels of `max_accepted_radius` (maybe with a slider).
3. Use some key to accept and save.

Step C: Manual cleanup
1. Use another callback to manually select triangles that should be removed.
2. Add callback key for "undo" last triangle removal.
3. Use some key to accept and save.

Basically, I have no idea how to plot the triangle wireframe with `VisualizerWithEditing`, but I suspect it's possible since it can be done easily with `draw_geometries`.

I also did not find how to use a callback to change the plotted geometry.

Any help is welcome!

Start by reading the `VisualizerWithEditing` and `draw_geometries` entry points in the release and latest documentation. Determine whether the requested wireframe display, geometry updates, sliders, selection callbacks, undo behavior, and save actions are supported; done means documenting the available path or defining the missing functionality.

Written by the indexing model from the issue text.