Adds a new subcommand to fork repos.
To specify the repo to fork, use the `--repo` flag. This feels a bit weird, other tea commands would put this as the first argument.
I decided to follow the flag style, as this is what all other subcommands of `tea repo` do. We might want to reconsider and make the primary subject of such commands an argument, instead of an required flag.. see #430
Co-authored-by: Norwin <git@nroo.de>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-on: https://gitea.com/gitea/tea/pulls/410
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Norwin <noerw@noreply.gitea.io>
Co-committed-by: Norwin <noerw@noreply.gitea.io>
