Borrowed from Tracker, this script has different mode usages:
* --sha allows specifying a commit SHA, HEAD^ by default.
* --dry-run shows suggested changes in stdout, by default
the local tree is changed.
* --rewrite amends the last commit, in addition to performing
the changes.
This allows from simple style checks in the development tree,
automatically rewriting with the suggested changes (e.g. with
`git rebase --exec ./check-style -r`) and CI integration.
The script has per-function granularity, and works by re-styling
individually every commit, and inside every commit every chunk.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1924>
