Well-known CORS container attribute

[roman-khimov]

Is your feature request related to a problem? Please describe.

I'm always frustrated when I think of nspcc-dev/neofs-s3-gw#1144.

Describe the solution you'd like

Add a well-known container attribute for CORS settings. It'd be a generic attribute in that REST would use it too. The value of it is JSON representation of S3 settings (https://docs.aws.amazon.com/AmazonS3/latest/userguide/cors.html), it seems to be generic enough for all use cases, but this can be checked.

Related to nspcc-dev/neofs-contract#449.