Create group issue boards API endpoint
Follow up of:
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2467/diffs
Description
Expose column lists, similar to https://docs.gitlab.com/ee/api/boards.html for project boards.
Out of scope
Saved config API is to be worked on separately here: https://gitlab.com/gitlab-org/gitlab-ee/issues/4266
Edited by Victor Wu