WIP: Design - Kubernetes First Iteration

In response to:

• https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/4858#note_104751344
• https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/5158

Review: https://jts-design-doc-k8s-iteration-1.about.gitlab.com/handbook/engineering/infrastructure/design/201810_KubernetesInterationOne.html