Add an option to activate or deactivate silent printing at a station

[mariobehling]

Silent printing allows attendees to simply scan their QR code and the printer will automatically start and print out their badge.

It should be possible to enable or disable this option at a station.

Also compare this previous PR https://github.com/fossasia/open-event-checkin/pull/111/files

[cweitat]

@mariobehling this is impossible on a website code level as it inteferes with the system print dialog. it has to be done on the application level