s3 uploads #543

[metame]

PR Checklist:

• Link to related issues: Feature: Atomic Server can store blobs on S3 compatible storage - like AWS S3, Cloudflare durable objects #543
• Add changelog entry linking to issue, describe API changes
• [-] Add tests (optional)
• (If new feature) add to description / readme

Open issues:

1. The data browser preview is currently not working for s3 files. This is likely because the download endpoint does a 302 temporary redirect to a S3 signed URL. I'd be happy to open a new issue for this for someone to fix that is familiar with the client side code.
2. Currently the config only requires S3 bucket to be specified. This is in line with opendal's requirements. The main callout here is that we are depending on opendal's default for region, which is "us-east-1". I could specify this directly in atomic's source code or we can make this a required config value.