Annoyed by having to regen the yarn lock by hand several times this week, I've decided to create a manually-runnable GH action that can save me the time of locally developing a PR for a yarn.lock update.

This can also be used to streamline the process for pr checksand pushes from the janus plugins repo.

Also merged the two required tests in the PR check into a single one, so we need to update the openshift CI config at https://github.com/openshift/release/pull/54882