add file hashes to file table

[jen-thomas]

Some larger files were uploaded to object storage in chunks and therefore have etags that end with - (see Background notes in the readme.md of this repo: https://github.com/Swiss-Polar-Institute/data-copy-verification).

Write a command to download the files that currently have an etag with -, calculate the file hash and insert this into the file model. Add the file hash of the smaller files to the hash field.