[Feature Request] Standardize available S3 features

In practice the SCS-IaaS mandatory "S3 API" is not well defined, given its sorry state of being a proprietary Amazon product, not a standardized thing. Basically all clone implementations I know of support a (different) subset of S3 features, especially those relevant here, such as Swift and Ceph.

• Garage has a nice overview comparing the different solutions that are around: https://garagehq.deuxfleurs.fr/documentation/reference-manual/s3-compatibility/
• Swift feature matrix: https://docs.openstack.org/swift/latest/s3_compat.html
• Ceph feature matrix: https://docs.ceph.com/en/latest/radosgw/s3/

So for example I can't use Bucket lifecycles to have a caching bucket expire automatically when the bucket lives on a Swift-backed S3. But currently I would have no idea that there might be such a limitation when buying a SCS-IaaS certified cloud (indeed had to learn that the hard way myself).

To be really clear, this has the potential to be certification-breaking and require quite some effort from CSPs if it is decided to require a more complete set of S3 features, since they might have to migrate their S3 service to completely different solution then.

I'm not clear how representative my experience is for other users/SCS-IaaS Cloud customers, I'll try to get some more opinions on that.