Add support for kustomize deployment

[ramizpolic]

Goal

We would like to provide a way to deploy operator using kustomize leveraging kubebuilder. This requires adding the deployment and updating necessary RBAC policies.

Use https://github.com/bank-vaults/vault-operator/tree/main/deploy/charts/vault-operator as a reference.

Ensure that documentation guide works for Vault CRs added to a default, as well as custom namespace.

[cjyar]

As an alternative, users could use kustomize's helmCharts support. However, kustomize doesn't support helm charts with the oci:// scheme (kubernetes-sigs/kustomize#4381). If bank-vaults offered an https helm registry, that would work.

[ramizpolic]

That does pass all the heavy lifting away from us, which is awesome @cjyar. Referenced PR kubernetes-sigs/kustomize#5167 seems to be ready for merge, so we can probably expect the release sometime soon.

[cjyar]

Kustomize now supports helmCharts with an oci:// scheme. That support has been taken up by argo-cd, which meets all of my needs. It's possible that that's enough for the other users of bank-vaults also.