Allow adding groups to CODEOWNERS file

What does this MR do?

Allow adding groups to CODEOWNERS file

Groups can be specified by their path and then the users of these groups are displayed as code owners

CE Backports MR: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/29533

Issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/53182

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content