Bypass for Domain-level redirects (Unvalidated Redirects and Forwar)

While testing for the ability to define custom redirects in Gitlab Pages, I discovered I was able to define `Domain-level redirects` which are explicitly disabled in the documentation. At a first glance, the validation step seems to disable any link not starting with `/`, It has however to be noted …

6. Wait for the CI to complete the deploy
7. Navigate to the defined redirect
8. Verify that the redirect is reaching an external website

### Impact

An attacker may define vanity URLs hosted on GitLab targeting phishing websites.

### Examples …