Enable requiring IMDSv2 on new AMI registration

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**Tell us about your request**
The [security best practices for EC2 Image Builder][sbp] document recommends requiring IMDSv2:

> We recommend that you configure all EC2 instances that Image Builder launches from a pipeline build to use IMDSv2
> so that instance metadata retrieval requests require a signed token header.

Yet there is no option to enable IMDSv2 on output AMIs. That has to be done after-the-fact using a ModifyImageAttribute call.

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
It's not so much difficult as it forces us to take an extra step outside of image builder to configure the image before it can be used in our environment.

**Are you currently working around this issue?**
Using ModifyImageAttribute to modify the AMI after the fact to require IMDSv2.

**Additional context**
IMDSv2 is required for all EC2 instances in use at my company. It's easiest to bake this into the AMI from the get-go.

**Attachments**
N/A

[sbp]: https://docs.aws.amazon.com/imagebuilder/latest/userguide/security-best-practices.html

Start by reading the EC2 Image Builder security best-practices document linked in the issue and reviewing the current ModifyImageAttribute workaround. Determine where output AMI registration would accept an IMDSv2 requirement; done means a supported option configures newly registered output AMIs without a post-build modification.

Written by the indexing model from the issue text.