Hook up to Quay.io or OpenShift CI

[jlebon]

I'd like to be able to write upgrade tests that require talking to a local dumnati server serving test-specific metadata. I'd much prefer just pulling down a container instead of rebuilding it locally as part of the test. :)

Easiest would be to hook it up to Quay.io or https://api.ci.openshift.org/. An alternative for users is pulling directly the image built in the Fedora OpenShift project, though offhand it doesn't look like the registry is exposed.

[lucab]

We are now using GH actions for ignition-validate, we can likely do the same here too: coreos/ignition#1336

[lucab]

Just for clarity, the result of this would go into quay.io/coreos/fedora-coreos-cincinnati.