[EKS] [request]: Elastic IP for EKS API server endpoint

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**Tell us about your request**
We need Elastic IP for EKS API server endpoint to limit public IP address to the EKS endpoint for better security.

**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?**
I only grant access to API server endpoint from office static IPs and OpenVPN elastic IP.

I am running an OpenVPN inside the VPC and push EKS API server endpoint IPs to the OpenVPN route.
Time to time, EKS endpoint IPs are changing.
For that reason my VPN route does not work anymore and I can't run `kubectl` commands.
I would like have elastic IP address for EKS API server endpoint hostname.

**Are you currently working around this issue?**

If the problem happens, I update the VPN push route and restart the VPN service.

No files, tests, or code entry points are named. Start by examining the EKS API server endpoint and its changing IPs in the context of the VPC OpenVPN route; done means the endpoint can use a stable Elastic IP so the VPN route and kubectl access remain valid.

Written by the indexing model from the issue text.