[EKS capabilities] [request]: Allow adding Config Management Plugins for EKS managed Argo CD

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**Tell us about your request**
I want to add CMP to allow helm chart deployment through kustomize. Right now this is limiting us from deploying through kustomize.

**Which service(s) is this request for?**
EKS ArgoCD capabilities

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
As described in this [document](https://docs.aws.amazon.com/eks/latest/userguide/argocd-comparison.html), Config Management Plugins (CMPs) for custom manifest generation is not supported.

**Are you currently working around this issue?**
How are you currently solving this problem?

**Additional context**
Anything else we should know?

**Attachments**
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