Summary:
This adds our first Kustomize scripts.
Will remove the original YAML templates once Kustomize stuff is done.

Test Plan: `kustomize build k8s/customer_docs/nightly`

Reviewers: oazizi, michelle, #engineering, philkuz

Reviewed By: #engineering, philkuz

Differential Revision: https://phab.corp.pixielabs.ai/D1140

GitOrigin-RevId: 9721d8308e302a10564d95ac5a04c30ef413e4ab