3D model search path

[ferdymercury]

The archive project plugin works nicely, but there is an issue if one defines a 3D model search path (not an environmental variable), see https://forum.kicad.info/t/help-understanding-3d-search-paths-and-environment-variables/20726

In this case, the footprint is just ABCD.step and the plugin is unable to find it and copy it to the archived folder.

I found a hacky workaround, namely to add in line https://github.com/MitjaNemec/Kicad_action_plugins/blob/master/archive_project/archive_project.py#L582 the following:

if not model_path.startswith('$') and not model_path.startswith('/'):
    model_path = '/My3dsearchPath......../' + model_path

Probably there is a way to generalize so that a fix can be commited to master?