oxidizing gitui (migration to `gitoxide`)

[cruessler]

This is a tracking issue for oxidizing gitui. I’ve only collected the areas that already have at least one PR. I want to add more context and details over time. I hope I didn’t miss any existing tracking issue on the same topic. :smile:

High-level

• [ ] status
  • [x] tree view (#2673)
  • [ ] diff view (#2685)
• [x] tags (#2664)
• [ ] branches (#2706)
• [ ] blame (#2591)
• [x] log view without filter (#2275)
• [ ] log view with filter

Low-level

• [x] get_commit_info (#2654)

Clean-up/refactor

Some of the following refactorings might not be possible yet, but depend on other work to be finished before we can start working on them.

• [x] extract function gix_repo(), similar to repo(), that wraps current gix::ThreadSafeRepository::discover_with_environment_overrides(repo_path.gitpath()).map(Into::into)?
• [ ] either remove untracked_files_config_repo in case it is not needed anymore or change it to match git behaviour
• [x] extract gitoxide-related errors into a separate error variant GixError to keep them in a single place (#2687)