Hydra based OAuth Service

• Integrate Hydra as a library into a new Golang service
• Implement OAuth endpoints for authorization code flow
• Configure default OAuth clients
• Implement hand-off to GitLab Rails for consent
• Implement OAuth client retrieval endpoint (from Hydra using the consent challenge)
• Build custom consent screen UI in GitLab Rails using client details from the IAM service
• Store user consent in GitLab Rails
• Redirect back to OAuth Service with consent decision