oxidize `zed`

[Byron]

https://github.com/zed-industries/zed

Diffing

• [x] blob-diff based on two buffers
• [ ] diff-delta (probably works via imara diff already, but exact format is unclear)
• [x] line-stats
• [ ] hunk by index (probably works via imara-diff, but needs validation)

Status

What matters is that the information is complete - maybe they'd use plumbing for this. A trait exists to make other backends easier.

• [x] index-and-worktree, filtered by pathspec (i.e. subdir or single-file filter)
• [ ] commit-and-index (by path)
• [ ] status of worktree file (to get untracked, conflicts, ETC)

Other

• [x] open thread-safe repo
• [x] current branch name
• [x] list branches
• [x] crate a new branch
• [ ] rename branch (no native support, must be deletion and creation), unclear if rename should be native rather than having a transaction with delete and create.

For tests

• [x] init non-bare
• [ ] add file to index and write it back (git add)
• [ ] git rm --staged
• [ ] git commit - write tree from index (!), create commit
• [ ] git stash
• [ ] git reset --soft <commit>
• [ ] git status - for paths and their status