Ability add event-based terms and conditions, and privacy policies

e.g if privacy policies ask explicit consent to share event-based data with event's partners. This feature adds the ability to add event-based T&C and PP for registration.

If there is only an e.g. one line to be added this makes it easier

No files, tests, or entry points are identified in the issue. Start by tracing the registration flow and how terms, privacy policies, consent, and event partners are represented. Done means organizers can add event-specific terms and privacy-policy consent requirements, including a single-line addition, and registrants can encounter them during registration.

Scritto dal modello di indicizzazione a partire dal testo della issue.