[EKS] [request]: Support Instance Market Options of Spot instances for managed node groups

### 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**
Managed node group can support spot instance market option for setting max price.

**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?**
As EKS managed node groups supports [Spot instance feature](https://github.com/aws/containers-roadmap/issues/583), by default it is using optimal Spot max price to ensure capacity provisioning and bid with low cost. But I am wondering if I can define lower Spot max price in managed node group or my launch template, which can offer cost-effective option to run flexible jobs (e.g. batch processing) that can start/stop anytime.

However, right now, it is not supported and the selection can be blocked with following message if choose launch template that defined maximum price when creating managed node group:

```
Instance market options (EC2 Spot) are not supported in launch templates used with Managed Node Groups.
```

**Are you currently working around this issue?**
Using self-managed node group

**Attachments**

(In the advanced detail of the launch template can define maximum price)

The payload identifies EKS managed node groups, EC2 Spot instance market options, and launch templates, but no source files or tests. Start by reviewing the linked Spot feature issue and the launch-template rejection described here. Done would mean a managed node group can use a configured lower Spot max price without that rejection.

Written by the indexing model from the issue text.