Add user/license metrics for self-hosted
Summary
We are an organization using GitLab Ultimate Self-Hosted. Our leadership would like us to dashboard user count/license usage metrics as they don't get admin access to GitLab (SOD reasons).
We would like to see the exporter start exporting the same user metrics we see in the admin dashboard in GitLab so we can dashboard those metrics in a utility our leadership does get access to:
- Users in License
- Billable Users
- Maximum Users
- Users over license