[ECR Public] [request]: Lifecycle policies

### 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**
Would be great if ECR Public supported lifecycle policies (which are [supported by ECR](https://docs.aws.amazon.com/AmazonECR/latest/userguide/LifecyclePolicies.html)).

**Which service(s) is this request for?**
ECR Public

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Want to ensure we don't break deployments by hitting [repository image limits](https://docs.aws.amazon.com/AmazonECR/latest/public/public-service-quotas.html).

**Are you currently working around this issue?**
No; not yet close to hitting the limits. Currently old images have to be manually removed (if needed).

**Additional context**
Consistency with the [ECR lifecycle policies](https://docs.aws.amazon.com/AmazonECR/latest/userguide/LifecyclePolicies.html) would be great.

**Attachments**
N/A

Start by reviewing the ECR Public request and the linked ECR lifecycle policy and public service quota documentation. Define what lifecycle-policy support must cover and consider the request complete only when ECR Public can consistently manage old images without exceeding repository image limits.

Written by the indexing model from the issue text.