Implement option for organisers to deactivate "Continue as a Guest"

[mariobehling]

When buying a ticket attendees have the option to get a ticket as a guest choosing the option "Continue as a Guest".

Implement an option for organisers to make this optional. If the organiser chooses the option "Only allow registered accounts to get a ticket" the "Continue as a Guest" option will not be available for attendees.

The option should be implemented on the organizer tickets page, e.g. like here https://app.eventyay.com/tickets/control/event/wiorg/wikiindaba/settings/tickets

If this option is choosen also remove the bottom feature "Resend order links" on the ticket page.