Restricted files are not mentioned in the Dublin Core record

[mmo]

Files that are under embargo do not appear in the oai_dc (Dublin Core) export.

Bug description:

Examples:

Thesis with a single, publicly accessible file:
https://sonar.ch/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai:sonar.ch:309534
https://folia.unifr.ch/unifr/documents/309534
The file is indicated in the oai_dc record (field dc:identifier)

Thesis with multiple, publicly accessible, files:
https://sonar.ch/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai:sonar.ch:328849
https://folia.unifr.ch/unifr/documents/328849

Thesis with a single, restricted access file:
https://sonar.ch/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai:sonar.ch:326572
https://susi.usi.ch/usi/documents/326572
Le fichier ne figure pas dans la notice oai_dc

Thesis with two files, one is publicly accessible and the other has restricted access:
https://sonar.ch/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai:sonar.ch:328193
https://folia.unifr.ch/unifr/documents/328193
Only the publicly accessible file is included in the oai_dc record.