Get resource by id

[yellalena]

• Add GET /resources/<id> endpoint
• Dynamically calculate hiddenFrom field value for the record, add it to frontend’s output. Since hiddenFrom is a field for frontend, it should use frontend’s terminology, i.e. guest instead of public
• Based on hiddenFrom and requestor’s role, return either full resource data or 403
• Build attachment's link using attachment_filename and s3. Refer to applications to see how it's implemented
• Update swagger
• Add unit tests