Add the ability to set the PublicAccessBlock config on S3 buckets

Even though S3 buckets/objects do not allow public access by default, a best practice is to explicitly disable public access to prevent inadvertently making a bucket/object public in the future.

This can be accomplished by making a request to [`put_public_access_block()`](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/s3.html#S3.Client.put_public_access_block) & setting all of the values in `PublicAccessBlockConfiguration` to "True".