Changes to List Files

added the new agentic_safety enum value to the data/items/purpose response property for the response status 200

added the enum value agentic_safety to the property anyOf[subschema #1: FilePurpose]/ of the query request parameter purpose

added the optional property data/items/expires_at to the response with the 200 status

added the optional property data/items/visibility to the response with the 200 status

added the new optional query request parameter mimetypes