Support S3 compatible state stores

[codynhat]

Description

It would be great to support other S3 compatible stores as the state store. I am currently unable to get Digital Ocean Spaces to work, as it needs the endpoint to be changed.

Technical Information

S3LevelDown is currently being used for the S3StateStore implementation. Their docs have an example of how to configure other S3 stores like Min.io. I believe this would require a few more config parameters, notably a custom endpoint.

[avious00]

@codynhat i crossposted this to our forum https://forum.ceramic.network/t/support-s3-compatible-state-stores-re-post-from-gh/390 so our engineers can see this and reply, and i also added this is to our feedback/feature request tracker

[codynhat]

Thanks!

[stbrody]

We'd welcome a PR for this!