kubergrunt eks configure should allow you to force update an existing context

When you reuse EKS cluster names, the ARNs stay the same if the EKS cluster is recreated, but since the server parameters change (e.g., the endpoint and the CA certificate), you need to reconfigure the kubeconfig. However, `kubergrunt` currently errors out if a context and config already exists for the server with the same ARN.

The workaround is to delete the existing config, but `kubergrunt eks configure` should also expose a `--force` option to overwrite the existing config instead of erroring out.