Add gitlab api access
split out from !2155 (merged) to make it easier to review.
This MR adds methods to access the gitlab api. It leverages gitlab-shell's client. It also modifies the Gitlab Test Server so it accepts Json as well as form data, which is what the gitlab internal api does.
This code essentially ports https://gitlab.com/gitlab-org/gitaly/-/blob/master/ruby/gitlab-shell/lib/gitlab_access.rb to go
it also modifies the test Gitlab Server to handle json
Edited by GitLab Release Tools Bot