com-lihaoyi
Vendor `lefou::mill-vcs-version` as part of `mill-main` (backport #4842)
This PR vendors a copy of https://github.com/lefou/mill-vcs-version inside the Mill repo.
mill-vcs-version is necessary for re-bootstrapping on top of main.
mill-mima or mill-scalafix are linters that can be disabled during
the re-bootstrapping process and turned on again later when the
third-party plugins are available, but mill-vcs-version is needing to
compute versions during the bootstrapping/dogfooding process and cannot
simply be skipped.
An alternative would be copy-pasting code into build.mill as a
temporary hack, but I think it's better to just vendor a full copy of
the upstream codebase. mill-vcs-version is a pretty small and stable
codebase, so the overhead of maintaining a vendored copy should be
manageable.
Original pull request: https://github.com/com-lihaoyi/mill/pull/4842
