Auto merge of #13592 - Byron:gix-for-list-files-git, r=arlosi

Use `gitoxide` for `list_files_git`

Related to #10150.

### Tasks

* [x] update `gix` to v0.60
* [x] assure this is tested (currently only git-tests run with `git2` and `gitoxide`)
* [x] allow `list_files_git` to use `gitoxide` if it is enabled as feature.
* [x] use dirwalk iterator
* [x] 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.

Author: bors

.github/renovate.json5

@@ -67,16 +67,6 @@
       internalChecksFilter: 'strict',
       groupName: 'msrv',
     },
-    {
-      matchManagers: [
-        'cargo',
-      ],
-      matchPackageNames: [
-        'gix-features-for-configuration-only',
-        'gix',
-      ],
-      groupName: 'gix',
-    },
     // Goals:
     // - Rollup safe upgrades to reduce CI runner load
     // - Have lockfile and manifest in-sync (implicit rules)