Add EKS extended support version rule

What

Flag EKS clusters running a Kubernetes version in (or approaching) extended support, where the cluster fee jumps from $0.10 to $0.60 per hour.

Why

Extended support raises the base cluster fee from ~$73 to ~$438/month per cluster — a 6x increase that arrives silently when a version ages out of standard support. This is the exact analog of CLDBRN-AWS-RDS-6 (unsupported engine version), which CloudBurn already ships for RDS, and the EKS module has only one rule today (EKS-1, Graviton).

Details

• Compare cluster version against the EKS standard-support calendar; flag clusters already in extended support (high severity) and optionally those entering it within a review window.
• IaC + discovery: Terraform aws_eks_cluster.version / CloudFormation AWS::EKS::Cluster Version, plus the live cluster dataset.
• Extends packages/rules/src/aws/eks/ as CLDBRN-AWS-EKS-2.
• Research question: how to keep the version-support calendar current — a curated static table in the rules package (same approach as curated Graviton/instance-family sets) is the likely answer.
• Per repo policy, static coverage tested against both Terraform and CloudFormation inputs.

Start in packages/rules/src/aws/eks/ by reading the existing EKS-1 rule and compare it with CLDBRN-AWS-RDS-6. Trace how Terraform aws_eks_cluster.version, CloudFormation AWS::EKS::Cluster Version, and live cluster data are tested. Done means CLDBRN-AWS-EKS-2 identifies extended-support versions and has static-coverage tests for both IaC inputs.