Polus plugins : Fix how plugin names are generated

[agerardin]

Summary

polus plugins ingest names from the plugin manifest.
In order to make them valid properties of polus plugins, their names need to be transformed.
However, the manifest returned to the user has no mention of this and this prevents the user to know how to refer to his plugin, except through manual inspection. This is a usability issue.

Possible fixes

We could tackle two different ways.
1/ Enforce certains rules for names in the plugin manifest so that they can be used as properties.
2/ Explicitly add a plugin_id or plugin_handle to to the manifest that is documented and that can be used to refer to the plugin later from polus-plugins
3/ modify all methods so that names are transparently translated if needed.

Steps to reproduce

Example of client code :

        manifest = pp.submit_plugin(plugin_url, refresh=True)
        # name_cleaner is polus_plugins internal code
        plugin_classname = name_cleaner(manifest.name)
        pp.refresh()
        cwl = pp.get_plugin(plugin_classname).save_cwl(cwl_path / f"{plugin_classname}.cwl")