[EKS] [Security] Allow restricting access to EKS Kubernetes Public API Endpoint by security group

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**Tell us about your request**
#108 added the ability to define an allow-list of CIDRs that can reach the Kubernetes API endpoint. We would like the ability to manage this allow-list using a security group.

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
We have existing tooling built around security groups. We use their tags and the fact that individual ingress or egress rules on a security group can have descriptions in automation that analyses rules and can revoke them if they are expired or invalid. The existing API server allow-list only lets you specify a list of CIDRs in a call to `UpdateClusterConfig`, so there is nowhere to store metadata, and even if there was, we would have to write some new code to achieve parity with the current tools built on security groups.

Start by reviewing issue #108 and the EKS UpdateClusterConfig API behavior described here. Determine how the Kubernetes public API endpoint allow-list could be managed with security groups, including the tags and ingress or egress rule descriptions used by existing automation; done means the requested security-group-based restriction is defined and supported.

Written by the indexing model from the issue text.