remove `ActAs` role

[T0nd0Tara]

I've noticed it is very hard to remove a role in this plugin, i.e. I can change the role to be Yes or No answer for example. but I cannot revert it to be the original chat gpt.

I think the most UX way to add this feature is to add a regular option in the ActAs window. but I've noticed the plugin fetches the roles from another github repository.

So I believe a machanism to add custom roles inside the plugin (maybe even let the user add custom roles) would be a great feature.