This simplifes the mental model on how it works and simplifies testing
of the related code.
This also normalizes storage object deletion in the same way as the
rest of objects in penpot (now future deletion date on storage object
also means storage object to be deleted).
* 📎 Set proper name to relink-refs mechanism function
* 🐛 Fix incorrect id assignation on snapshot file resolution
* ♻️ Use uniform api for file retrieval on file snapshot code