EKS DeleteNodegroup: add response details in API call to identify if this call is going to make changes in aws-auth configmap

### Community Note

* Please vote on this issue by adding a 👍 [reaction](https://blog.github.com/2016-03-10-add-reactions-to-pull-requests-issues-and-comments/) to the original issue to help the community and maintainers prioritize this request
* Please do not leave "+1" or "me too" comments, they generate extra noise for issue followers and do not help prioritize the request
* If you are interested in working on this issue or have submitted a pull request, please leave a comment

**Tell us about your request**

DeleteNodegroup API in EKS should provide details weather it is going to change aws-auth configmap or not.

This will help to avoid issues when same IAM role is used in self managed node grous as well.
```
If you delete a managed node group that uses a node IAM role that isn't used by any other managed node group in the cluster, the role is removed from the [aws-auth ConfigMap](https://docs.aws.amazon.com/eks/latest/userguide/add-user-role.html). If any of the self-managed node groups in the cluster are using the same node IAM role, the self-managed nodes move to the NotReady status. Additionally, the cluster operation are also disrupted. You can add the mapping back to the ConfigMap to minimize disruption.
```

**Which service(s) is this request for?**
EKS

**Are you currently working around this issue?**
Need to check manually

**Additional context**
NA

**Attachments**
If you think you might have additional information that you'd like to include via an attachment, please do - we'll take a look. (Remember to remove any personally-identifiable information.)

Start with the EKS DeleteNodegroup API and the referenced aws-auth ConfigMap behavior. Define the response detail needed to identify whether deletion will change the ConfigMap, including the shared IAM-role case; done means callers can determine this before disruption occurs.

Written by the indexing model from the issue text.