How to use the BackupChecks with a S3 disk

[craigpotter]

How would you use this with a S3 disk?
Currently you can use the locatedAt() but that only accepts a glob.

Am I right in thinking this check would only work for local backups?

[freekmurze]

This now only works for local backups indeed.

I welcome a PR that would add a onDisk($diskName) method. The check would then have to loop through all files on that disk (I don't think there is a glob like function for disks.