📎 : Other

There's a lot of duplication in the various setups used in the current test steps, it would be nice if we could reduce this into a sane "basic setup" so that people don't have to guess at the various Magento setup steps as things break across time.

Prior Work

https://github.com/mage-os/generate-mirror-repo-js/blob/main/.github/actions/checkout-magento/action.yml#L1

Is probably a close equivalent that originated from this repo.