DevSecOps : use new EKS api access instead of Configmap

Some customers updated the cluster to use only the API, so when using this module, they couln't use any more the aws-auth config map.

We should update the module to use EKS access management API instead:

https://catalog.us-east-1.prod.workshops.aws/event/dashboard/en-US/workshop/12-image-security/3-devsecops-pipeline/1-solution-architecture-devsecops-pipeline-pushing-containers-to-eks/1b-create-iam-role

```
eksctl create iamidentitymapping \
--cluster eksworkshop-eksctl \
--arn arn:aws:iam::${ACCOUNT_ID}:role/EksWorkshopCodeBuildKubectlRole \
--username build \
--group system:masters
```

Locate the module's handling of the aws-auth ConfigMap and review how the EKS access management API should replace it. Use the linked IAM role and eksctl create iamidentitymapping example as context; done means customers using API-only cluster access can use the module without relying on aws-auth.

Written by the indexing model from the issue text.