operator: implement build phase

[toms-place]

defining outputs for jobs: https://docs.github.com/en/actions/using-jobs/defining-outputs-for-jobs
docker build push action: https://github.com/docker/build-push-action/tree/v4/
semver release: https://github.com/ietf-tools/semver-action

using buildah to do rootless builds: https://github.com/containers/buildah/blob/main/docs/tutorials/05-openshift-rootless-build.md

[toms-place]

Ideas:

• Use https://pkg.go.dev/text/template#Template to create scripts and dockerfiles.
  • see examples to load files or this article: https://blog.gopheracademy.com/advent-2017/using-go-templates/#implementing-templates
• Use environment vars for jobs and execute them like so: echo $my_script | sh