[EKS] [request]: 1-click upgrades support blue/green or reversibility

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**Tell us about your request**

In this year's re:invent's EKS deep dive, the speaker mentioned that more and more customers were moving from 1-click upgrade to blue/green EKS deployments.
I'd like to see the option to blue/green the API server with the same "1-click" ease.
This will enable one of AWS' well architected framework best practices "[Make frequent, small, **reversible** changes](https://docs.aws.amazon.com/wellarchitected/latest/framework/a-prepare.html)"

**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?**
Reliable, reversible kubernetes upgrades currently require spinning up a new cluster and migrating workloads to it. This requires managing migration automation or spending resources on migration toil.

**Are you currently working around this issue?**
self-managed blue/green EKS deployments.

The request names Amazon EKS and self-managed blue/green deployments, but no repository files, tests, or entry points. Start by clarifying the desired EKS upgrade and reversibility workflow and its constraints; done would be an agreed implementation path for one-click blue/green upgrades or rollback support.

Written by the indexing model from the issue text.