Make CI linting checks run in package publication tools

[shonfeder]

As discussed in the maintainer meetings in the last weeks with @mseri and @raphael-proust, we can save quite a bit of manual back and forth and build time if we are able to ensure that packages created with dune-release and opam publish already pass linting checks before they are submitted as PRs here.

Thanks to @punchagan's work on https://github.com/ocurrent/opam-repo-ci/tree/master/opam-ci-check#opam-ci-check, we now have the CI linting logic exposed in a way that should make it pretty easy to share code between the publication tools and the CI, enabling us to push some of our integration-level checks earlier into the software development life cycle.