Login with GitLab is broken due to their V3 API no longer being supported

[alikhajeh1]

Logging in with GitLab shows an authentication error; the master logs show AuthenticationError: Could not retrieve GitLab id. The issue seems to be that GitLab's V3 API, which is used by Origin, stopped working tonight:

curl -i "https://gitlab.com/api/v3/user" -H "Private-Token: SECRET"
{"error":"API V3 is no longer supported. Use API V4 instead."}

If the GitLab code is being updated, it might also be nice to address #17954

Version

Origin 3.9

Steps To Reproduce

1. Setup Origin to Login with GitLab
2. Try logging in and notice the authentication error

Current Result

User can't login with GitLab.

Expected Result

User should be able to login with GitLab.

[aliscott]

Relevant GitLab discussion: https://gitlab.com/gitlab-org/gitlab-ce/issues/47565#note_80041904 (Consider bringing back v3 endpoint for OAuth endpoints)

[enj]

@openshift/sig-security