[ECR] [request]: ECR Image scanning does not support multi-arch images

### 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**
What do you want us to build?
What are the possible ways to scan multi-arch images? Will ECR be supporting the functionality of scanning of multi-arch image in the future
**Which service(s) is this request for?**
This could be ECR

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
What outcome are you trying to achieve, ultimately, and why is it hard/impossible to do right now? What is the impact of not having this problem solved? The more details you can provide, the better we'll be able to understand and solve the problem.

The multi arch build images doesn’t get scanned. we would like to know the alternatives for this and will ecr provide this feature in the near feature. I could see they are no documents specifying that ECR doesn’t support multi arch bild image scanning.

"https://docs.aws.amazon.com/AmazonECR/latest/userguide/docker-push-multi-architecture-image.html"

**Are you currently working around this issue?**
How are you currently solving this problem?

**Additional context**
Anything else we should know?

**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.)

https://docs.aws.amazon.com/AmazonECR/latest/userguide/docker-push-multi-architecture-image.html

No repository files or tests are named. Start with the linked Amazon ECR multi-architecture image documentation and compare its scanning behavior with the requested outcome; done would require a maintainer-confirmed ECR capability or documented alternative.

Written by the indexing model from the issue text.