Improve RBAC management for aws-auth

The [EKS module](https://registry.terraform.io/modules/terraform-aws-modules/eks/aws/latest) gives the ability to configure the `aws-auth` ConfigMap to give users and roles access to the cluster. That can be for administration or monitoring purposes using local tools like `kubectl` or Lens. The problem is that the EKS module appears to have a dependency problem where it attempts to apply configurations to `aws-auth` before the ConfigMap is set up. I'm not overly thrilled with the solution being to create the cluster with the `[manage_aws_auth_configmap](https://registry.terraform.io/modules/terraform-aws-modules/eks/aws/latest#input_manage_aws_auth_configmap)` option set to false, and then update the configuration with this setting enabled, which is an obvious hack.

This issue is to resolve this problem definitively. A solution might be to file an issue to the module github, or to develop a more complex solution in-house, or to just implement the hack described above as a stop-gap.

Start by reviewing the EKS module's aws-auth ConfigMap configuration and the manage_aws_auth_configmap input, then reproduce the dependency ordering problem during cluster creation. Compare the available module behavior with the proposed two-step workaround and determine which approach gives a reliable initial cluster setup; done means aws-auth is configured without requiring a manual stop-gap.

Written by the indexing model from the issue text.