[FEATURE] Allow Appointments to be applied to guest registrant

[tcdahlberg]

Use case

A registrant has entered guest registrants that they are bringing. On the appointment page they have a variety of options for their event. The registrant would like to be able to add guest registrants they have entered to have the same appointments per guest. This might be a checkbox next to each registrant name under each appointment.

When the guest registrants are added to an appointment they will get that appointment also applied to their registration.