Create (or update) a data type for representing a comprehensive "Contact"

PA has had several use case for a role-specific contact.  For example, Organization.contact.  This include an address, telecom, HumanName, and role.  There has also been discussion about adding a period to represent the effective time range for the contact, but that has been more controversial.

We wanted to propose making a data type that could represent this without duplicating a backbone element.  Alternatively we could expand ContactPoint, but that seems more disruptive.

BR&R expressed interest in being involved in discussions about this data type (specifically, Petere Bomberg)