feat(cmd/mr): make mr wip and ready handle all recognized GitLab keywords

turns out[1] that GitLab recognizes more than just WIP: and [WIP], it also has new keywords: [Draft], Draft:, and (Draft).

the WIP ones are being deprecated and won't be present in 14.0 so we are supporting them until all instances that we recognize upgrade to 14.0.

[1] https://docs.gitlab.com/ee/user/project/merge_requests/work_in_progress_merge_requests.html