[gitlab-oauth-plugin] Add basil to gitlab-oauth

[Basil Crow]

Sending this email as requested by Mark Waite. As described in
jenkins-infra/repository-permissions-updater#2071, I have no actual
interest in maintaining this plugin, but I need
jenkinsci/gitlab-oauth-plugin#31 merged and released to facilitate the
core Guava upgrade. Since I have not received a response from the
current maintainer (Mohamed EL Habib, CC'd in this message), and since
I do not think it is acceptable to break this plugin, I suppose I just
need to do it myself. I do not really have a way of testing this
plugin in a realistic environment, so I will try to recruit some users
to help me. Failing that, I will monitor Jira for any regressions and
respond to them accordingly. I may keep maintaining the POM/BOM and
merging/releasing minor bug fixes, but I can't promise major feature
development, security fixes, or in-depth code reviews.

Link: https://github.com/jenkinsci/gitlab-oauth-plugin
PRs: https://github.com/jenkinsci/gitlab-oauth-plugin/pull/31
GitHub username: basil
Jenkins infrastructure account ID: basil