Redirect "Event" button on events to alternate URL

Enable the “attend” button on event pages to redirect to a specific URL. 

Use case: using Events for calendaring on the community, but linking to a more robust events platform for ticketing, etc. 

Alternate use case: calendaring related events that are not “from” the community, but partners in the space. If another party owns the registration, but if there’s a desire for the community to direct traffic to external events. 

The link functionality doesn’t serve this need, because it’s still possible for someone to RSVP via the community event page, which could be a misleading user experience.