feat: use gix for parsing git information in mitre/git plugin

[patrickjcasey]

This pull request removes the need for a custom nom-based parser for parsing git information in the mitre/git plugin, by swapping over to using gix https://github.com/GitoxideLabs/gitoxide for parsing git information. As a part of this change, I got some data from the following repos:

• https://github.com/mitre/hipcheck
• https://github.com/numpy/numpy

testing on https://github.com/linux/torvalds was skipped for time reasons

I investigated using libgit2 first, but the performance on larger repos was not ideal, and it was difficult to integrate caching into the code. gix (https://github.com/GitoxideLabs/gitoxide) has better support for caching and is written in pure Rust which is also nice for memory safety reasons.

for determining execution speed, the following command was run with the release version of hc on my M1 Macbook Pro with 32 GB RAM, the mitre/git plugin was also configured to run the release version:

time ./target/release/hc check --policy config/Hipcheck.kdl <REPO>

for testing main, commit 4f205afd6ba0afd98d0ba91dc742f2038f6ddc89 was used

Branch	Repo	# of Commits	# of CommitDiffs	# of Contributors	Last Commit	Execution Speed
main	mitre/hipcheck	529	529	20	2024-12-09T22:58:27Z	9.19 s
gix	mitre/hipcheck	529	529	20	2024-12-09T22:58:27Z	9.98 s
main	numpy/numpy	28436	28436	1898	2024-12-09T20:49:11Z	2m 49s
gix	numpy/numpy	37617	37617	2243	2024-12-09T20:49:11Z	4m 38s

git rev-list --count HEAD results:

• mitre/hipcheck: 529 is returned, which matches both implementations
• numpy/numpy: 37617 is returned, which matches the gix implementation

git log --pretty="%an %ae%n%cn %ce" | LC_ALL=C sort -u | wc -l results:

• mitre/hipcheck: 20 is returned, which matches both implementations
• numpy/numpy: 2243 is returned, which matches gix implementation

The main highlight of this pull request is the fact that the parsing of git-related information is handled by a git library, rather than our nom-based parser, which was missing commits and contributors for larger repos. At some point, a pass can be made to dive into the performance of the git plugin to find places for optimization

[patrickjcasey]

Closes #575

[j-lanson]

Thanks Patrick!