Please describe the feature

As a SDA-admin, I want to be able to fetch accession IDs (or stable IDs) via the admin API when accession IDs are mapped to files so that I can continue with dataset creation.

Acceptance criteria

• Some database code that we use for admin-api needs to be split. We need to separate the calls made by submitters vs. calls made by helpdesk or repository admins.
• They should be returned when we list the files for a user, if there is a stable_id return the accession id
• Tests verifying the changes are added
• The endpoint should NOT display the accession ids for submission users.

Additional context

Related comment https://github.com/NBISweden/BigPicture-Deployment/issues/282#issuecomment-2663320060

Estimation of size

small/medium/big

Estimation of priority

low/medium/high