Discussion: Consolidate CI tooling

[adambkaplan]

@otaviof raised a valid concern in a recent operator pull request shipwright-io/operator#28 (review). Our CI tooling - driven by GitHub Actions - has a lot of common concerns when it comes to deploying a Kubernetes cluster (KinD), verifying the cluster is functioning, and deploying an image registry. We have slight variations across the build, cli, and operator repositories, which over time will lead to drift and added maintenance toil.

We should aim to find common concerns so that we test Shipwright in a consistent manner, and capture this in a shared repository.

[otaviof]

Thanks for creating this issue, @adambkaplan! To mention, @coreydaley came up with git-submodules for Bats testing in the CLI project some time ago, and the approach has been working really well. We should consider the same approach for this issue, IMO.