* Adds support for NIX_SSHOPTS
* Properly uses the parsed port from URL (fixes#13337)
* Don't guess the HTTP endpoint, use the response of git-lfs-authenticate
* Add an SSH Git LFS test
* Removed some unused test code
Add several tests for git fetching:
- shallow-cache-separation: can fetch the same repo shallowly and non-shallowly
- shallow-ignore-ref: ensure that ref gets ignored when shallow=true is set
- ssh-shallow: can fetch a git repo via ssh using shallow=1