Ingest GitHub Enterprise

Summary:

A lister is needed for GitHub Enterprise, the self-hosted version of GitHub. Presumably the existing GitHub lister will work for these sites too.

GitHub Enterprise sites have GitHub Enterprise Server 3.8.2 or similar in the footer.

I have not been able to find many public GitHub Enterprise servers, but there may be more in the .edu TLD:

https://github.rpi.edu/repositories
https://github.molgen.mpg.de/repositories

Plan:

• Implement lister
• Implement loader
• docker: Run lister
• docker: Run loader
• Document lister
• Document loader
• Deploy on staging
• Call for public review
• Deploy on production

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