Use `gitoxide` for `list_files_git` by Byron · Pull Request #13592 · rust-lang/c...

Related to #10150.

Tasks

• update gix to v0.60
• assure this is tested (currently only git-tests run with git2 and gitoxide)
• allow list_files_git to use gitoxide if it is enabled as feature.
• use dirwalk iterator
• use new release of gix with necessary updates

Review Notes

As this PR has come a long way, I decided to keep a few of the steps leading up to the final state, showing the PR's evolution in the hope it helps the review.

• Would it be better to simply use gitoxide for this without a switch? I don't think
  it will cause more trouble than git2, and if there is an issue I will fix it with priority.
• In one test, the walk resolves a symlink to a submodule to individual files, including the .git/* folder contained in the submodule which is ignored by the walk, i.e. submodule/* does not contain it, but submodule-link/* does. This is fixed in the gitoxide version, and the git2 version.
• I noticed that symlinks are resolved for packaging and are allowed to point to anywhere, even outside of package root. I left it, but felt that maybe this should be reconsidered.

Remarks

• I love the test-suite! It's incredibly exhaustive to the point where it uncovers shortcomings in gitoxide, which I greatly appreciate.
• I also love git2 as it's API for many things leads to pretty idiomatic code, and sometimes I really have to work to match it. The example here is the initial dirwalk() method which requires a delegate as it doesn't just collect into a Vec like git2 does (for good reason). Turning that into an iterator via dirwalk_iter() makes it far more usable, and will definitely be good for performance as the dirwalk work is offloaded into its own thread.