Remove S3 dependency and use EFS for db.json

[keithcom]

Update terraform to remove the S3 resource and use EFS to access the db.json file

Notes

• serverless issue+comment about getting EFS on a serverless Lambda: Support for EFS in lambda function configuration serverless/serverless#7848 (comment)

[iandvt]

@ryan-roemer && @kevinmstephens - Should this issue be closed? If we migrated from S3 to EFS then we would need to find a replacement for lowdb-adapter-aws-s3.

[ryan-roemer]

I don't think we'd need a replacement per set for lowdb-adapter-aws-s3 as we'd be using local (well, network-mounted) FS where db.json already works in https://www.npmjs.com/package/json-server via local lowdb.

I think a fair question for potentially closing this issue is whether or not the complexity of EFS is larger than S3 and we should just stick with S3 to keep this learning project as easy as possible for folks learning/experimenting with both sls and tf.