Add custom appointment type button

[Ldepner]

I am working on an integration with Cliniko for another booking site - we have the additional functionality to be able to attach a form to a specific appointment type on our side, so that when the patient books the appointment, they are prompted to fill out a form. It would be great if there was an equivalent to the existing custom patient button in Cliniko, for appointment type - so that a Cliniko user could quickly jump out and set up the appointment type form on our side, before returning back to work in Cliniko. (Alternatively a feature to attach forms to appointment types in Cliniko would be great).