Mirror more data per repo and allow arbitrary user mirroring

[Brycey92]

Enable LFS and wiki mirroring, and use auth token for all repo mirrors Allow --mode user to fetch repos of arbitrary --user value Improve error handling and error clarity

I made a number of design decisions while writing this that you'll have to decide whether you like or not. Where possible, I attempted to avoid breaking existing command syntax.

[maxkratz]

Thank you for your PR, @Brycey92!

Enable LFS and wiki mirroring, and use auth token for all repo mirrors

This would break existing deployments that do not use an auth token (e.g., if one wants to mirror a public organization), right?

Allow --mode user to fetch repos of arbitrary --user value

I like that!

Improve error handling and error clarity

Well done.

[maxkratz]

One additional thought came to my mind: it would be nice if the mirroring of git LFS data and wikis would be configurable individually. Maybe not all users want to mirror a whole bunch of large(r) data files or the wiki information.