feat: configure gitlab groups from external oidc groups

General MR

Summary

This Merge Request adds the ability to configure GitLab users based on OIDC group membership. The impacted config is the gitlab-sso-provider secret that is deployed alongside the GitLab HelmRelease.

The following values can now be included in addons.gitlab.sso:

groups:
  groupsAttribute: ""
  requiredGroups: []
  externalGroups: []
  auditorGroups: []
  adminGroups: []

This addition is backwards compatible. If a user does not supply any groups in their GitLab values, the gitlab-sso-provider secret will still render a valid JSON object.

NOTE: That this is only a GitLab premium/ultimate feature.

Relevant logs/screenshots

GitLab Docs on configuring external groups - ref

Linked Issue

issue

Upgrade Notices

N/A