support git 2.29's `commit-graph` path-based Bloom Filters

[lhchavez]

This depends on #5757

Git 2.29 added an extension for commit-graph files such that they also contain a bloom filter to track modified paths in commits, which can make the implementation of path-based revwalks easier AND faster.

Once some of the changes in #5757 land, this work can start. Some of the tasks involved:

• [ ] Support for reading the changed path bloom filters from existing commit-graph files.
• [ ] Creation of revwalk functions that can filter by paths.
• [ ] Update of the revwalk functions so that they can take advantage of commit-graph metadata.
• [ ] Support for creating/updating commit-graph files with changed path bloom filters.

Relevant documentation:

• https://devblogs.microsoft.com/devops/super-charging-the-git-commit-graph-iv-bloom-filters/
• https://github.com/git/git/blob/master/Documentation/technical/commit-graph.txt
• https://github.com/git/git/blob/master/Documentation/technical/commit-graph-format.txt

[sgorilla]

@lhchavez I see the #5757 issue was not finished, though it seems like it got very close. I am quite interested in this functionality (and especially the fast single file commit lookup by path) for our project. Was there a blocker that made this whole thing non-viable or is it potentially close to being achievable?