[ACM] Create a kustomize function to remove namespace from cluster scoped CRs

[jlewi]

As described in kubernetes-sigs/kustomize#2498 a problem right now is that kustomize will apply the namespace transform to cluster scoped custom resources. As a result we end up setting namespace on certain cluster scoped resources. ACM doesn't allow this.

Related to kubernetes-sigs/kustomize#2498
Related to #4 Deploy with ACM

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[jlewi]

Prototype in kubeflow/kfctl#335

[jlewi]

Following: https://googlecontainertools.github.io/kpt/reference/fn/run/#declaratively-run-one-or-more-functions

The next steps are to make this configurable using a "client side" CRD resource. This way we can just list whatever resources we need to strip the namespace from.

[jlewi]

I'm getting the error:

caip-fl-bp   KNV9999: metadata.annotations must be a map

When trying to apply the latest manifests for Kubeflow using ACM.