[EKS] [request]: Update nodegroup and template at the same time

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**Tell us about your request**
We deploy a nodegroup and reference launch template through cloudformation.
When updating both the nodegroup and the launch template, we get an eks error:
```
Version and ReleaseVersion updates cannot be combined with other updates
```

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
EKS backend should be able to queue updates and perform two updates after each other.

**Are you currently working around this issue?**
Creating two cfn updates, one for the template and one for the nodegroup and run them consecutively.

This is a roadmap request rather than a code issue, and the payload names no files or tests. Start by reviewing the EKS update constraint and the reported CloudFormation workflow; done means nodegroup and launch-template updates can be handled consecutively without requiring two separate CloudFormation updates.

Written by the indexing model from the issue text.