Add a version consistency check

[tetromino]

Extract the version from version.bzl using sed.

For MODULE.bazel, we need to use buildifier to avoid confusion between skylib's version and our dependencies' versions.

[tetromino]

~NOTE: this is not ready to merge yet - broken with --experimental_enable_bzlmod. See https://github.com/bazelbuild/bazel-skylib/issues/386#issuecomment-1241174956~ should be good now