calendar: Re-enable support for ACLs with version 3 of the API

This was non-trivial. New API added:
 • GDataCalendarAccessRule

Due to how this new class overrides GDataAccessRule, it must be used in
place of GDataAccessRule for any interactions with the Calendar API.
This is essentially a soft API break for anyone who uses calendars. It’s
unavoidable.

https://bugzilla.gnome.org/show_bug.cgi?id=664353