feat: Enable mirroring non-forked repos

[ahpook]

This is a pretty simplistic change to add the ability to mirror repos which are not actually forks of upstream projects. This is useful for demos and testing but it also can be helpful if the public organization actually is the upstream, because the repo contains a project we own, so we're the top of the fork network.

Addresses #251

Readiness Checklist

Author/Contributor

• [ ] If documentation is needed for this change, has that been included in this pull request
• [x] run npm run lint and fix any linting issues that have been introduced
• [x] run npm run test and run tests
• [ ] If publishing new data to the public (scorecards, security scan results, code quality results, live dashboards, etc.), please request review from @jeffrey-luszcz

Reviewer

• [ ] Label as either bug, documentation, enhancement, infrastructure, maintenance, or breaking

[ahpook]

Marking this as a draft because I'm having a hard time validating whether it actually works. Want to run it through CI and get some more 👀 on it

[ahpook]

This is stale and I probably will not get to polishing it up; closing. 😢