* jmap: add UpdateContactCard and UpdateCalendarEvent funcs
* use JSON marshalling and unmarshalling into a map for toPatch()
implementations
* add updating ContactCards and CalendarEvents to tests
* add deleting ContactCards and CalendarEvents to tests
* make query response totals work when the value is 0
* tests: use CreateContactCard and CreateCalendarEvent funcs to create
objects in tests instead of using a different JMAP stack that works
with untyped maps
* move ContactCard from jscontact to jmap, as it is actually a JMAP
specification item, but also was causing too many issues with
circular references from jscontact -> jmap
* introduce Foo, Idable, GetRequest, GetResponse, etc... types and
generics
* first attempt at a Foo factory type for Mailboxes, needs to be
expanded to further minimize repetition
* add more specialized template functions to avoid repetition
* introduce ChangesTemplate[T] for *Changes structs
