HTTP endpoint for uploading new reports. Counterpart to keyserver's send_report and send_reports endpoints.
This endpoint can handle both single and multiple reports at once.

Reports are processed concurrently, in separate Tokio tasks - this speeds up the processing of multiple reports in case they need to be uploaded to Blob service.

Depends on D8968, D8940

Used Postman to send requests.

• Sent a single report (example content copied from local mariadb) - ensured it was stored in DDB
• Sent multiple reports - ensured they were all saved
• Sent malfolmed requests (missing fields, invalid fields, etc.) - responds HTTP 400 Bad Request