Combine Members and Groups settings pages

Resources

PM @victorwu | FE/BE @jivanvl | UX @tauriedavis

Background

https://gitlab.com/gitlab-org/gitlab-ce/issues/23007, https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7771, https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7944

Implementation strategy

Refactoring the navigation and settings pages altogether in one code release is extremely complicated and risky. We will take the incremental approach.

• In multiple issues, each which is to be released separately, combine sections, as specified in #23007 (closed). Also, adjust the cog menu appropriately.
• In the last issue, change the navigation from the gear/cog design to harmonize with the rest of the GitLab navigation, as specified in #23007 (closed).

Scope for this issue

• For a given project, combine the existing Members page and the Groups page into a single page.
• Call this single page the Members page.
• Update the gear/cog navigation. Combine the Members and Groups navigation menu items into one menu item called Members.

Technical implementation

Refer to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7771, https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7944 regarding previous discussions.