Add hash fields for files (md5/sha256/...)

It would be great if Directus would calculate hash(es) of uploaded files automatically and make the hash(es) available through the file's fields. My use case is that I sync some files to another system frequently and having hashes would allow me to skip files that are already up to date. I suggest adding md5 and sha256 hashes which are very common.

The hashing could be an opt-in feature but given that the hashing usually is not the bottleneck but rather i/o (especially with cloud storage) I'd even say that it could just be an always-on feature.

What do you think?