UC-28 - Export case report

[cudeso]

Implement generation of case reports from case data, as Markdown rendered to PDF.
Allow downloading of reports and store them as part of the case record, with audit logging of exports and downloads.
Optionally attach the generated report to a related MISP event by creating a MISP report and object.
Provide JSON export of the case, with optional inclusion of encoded attachments, and log these downloads in the audit trail.
Create a digital signature (hash) of the report. Add the hash to the header/footer text (R-NF-SEC-0004)