Create `bazel mod deps` hook

In rules_labgrid, we currently have a section in our pre-commit hook that keeps MODULE.bazel.lock files up-to-date:

printf >&2 'Updating lockfiles\n'
for ROOT in . e2e; do
  (
    cd "${ROOT}"
    if ! bazelisk mod deps --lockfile_mode=error &>/dev/null; then
      bazelisk mod deps --lockfile_mode=update
      exit 1
    fi
  )
done

Rather than hardcoding . and e2e, it probably makes sense to use the parent directories of all MODULE.bazel.lock files that aren't ignored by Git.