feat: data integrity using md5

[vasco-santos]

We have sha256 as an attribute in our bucket entries. This could enable us to use S3's GetObjectAttributesCommand to get the sha256 of this. However, we can't follow same pattern as dotStorage workers because CF Workers have an internal API for R2 that supports sha256, while S3 API is still not compatible.

Moved towards trying to integrate md5, with the assumption of ETag header having md5 https://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommonResponseHeaders.html in it and that we can use S3 Client for R2 with   ✅ Content-MD5

We get md5 ETag in base16 (thanks docs for not mentioning this anywhere 😘) wrapped with quotation marks and S3 client for PutObjectCommand expects the base64-encoded 128-bit MD5 digest of the message (without the headers) according to RFC 1864

Closes #58

[seed-deploy]

View stack outputs

• pr113-w3infra-UploadApiStack

  Name	Value
  ApiEndpoint	https://bo73qzf2bj.execute-api.us-east-2.amazonaws.com
  CustomDomain	https://pr113.up.web3.storage

• pr113-w3infra-BusStack

• pr113-w3infra-CarparkStack

• pr113-w3infra-ReplicatorStack

• pr113-w3infra-SatnavStack

• pr113-w3infra-UcanInvocationStack

• pr113-w3infra-UploadDbStack

[vasco-santos]

See:

1. wrote random CAR using w3up-client (custom to PR endpoint) to S3 https://s3.console.aws.amazon.com/s3/object/carpark-pr113-0?region=us-east-2&prefix=bagbaiera6k23fndacmzy3zxxk7ql3diylrczsomo2hchyg7ox4ucjrkeshba/bagbaiera6k23fndacmzy3zxxk7ql3diylrczsomo2hchyg7ox4ucjrkeshba.car
2. Lambda replicator ran https://us-east-2.console.aws.amazon.com/lambda/home?region=us-east-2#/functions/pr113-w3infra-ReplicatorS-ucanreplicatorhandler5EE-xIFhExB74pNT?tab=monitoring
3. made it to R2 https://dash.cloudflare.com/fffa4b4363a7e5250af8357087263b3a/r2/overview/buckets/carpark-staging-0/objects/bagbaiera6k23fndacmzy3zxxk7ql3diylrczsomo2hchyg7ox4ucjrkeshba%2Fbagbaiera6k23fndacmzy3zxxk7ql3diylrczsomo2hchyg7ox4ucjrkeshba.car

[olizilla]

it's always the string encoding surprise. They should make hash digests be self describing.