Adds collaborator management commands API reference: https://api.charmhub.io/docs/collaborator I will paste a screenshot of the successfully-tested commands in the comments --- - [x] I've followed the [contribution guidelines](https://github.com/canonical/charmcraft/blob/main/CONTRIBUTING.md). - [x] I've signed the [CLA](http://www.ubuntu.com/legal/contributors/). - [ ] I've successfully run `make lint && make test`. `make lint` - yes; `make test` takes >10 minutes spinning up an lxc, so no. - [ ] I've added or updated any relevant documentation. - [ ] I've updated the relevant release notes.