Migrate Express Auth + JWT Workshop into CYF-Workshops repo

MigraCode Barcelona have a workshop on auth and JWTs: https://syllabus.migracode.org/courses/introduction-3/course-content/nodejs/week-3

We should migrate this into the CYF-Workshops repo.

I'm not sure we want to add this into the curriculum plan itself for now, and there's open discussion about how/whether we should teach auth (see https://codeyourfuture.slack.com/archives/C012UUW69S8/p1699878344857599), but we should make sure this content is persisted for the future.