Download files via post request

[nfebe]

Summary

Currently, download requests are handled via a get request which can break in various ways.

For example, if the GET URL is too long and the servers MAX_URL_LENGTH (size) is reached a 404 is thrown as reported in #7935

Resolves: #7935

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)