Port addressee model for the Grantlee formatter to KContacts::Addressee

Summary:
We still add a few properties on top of that, some of which are
transitional until everything is in the right place. This also
already aligns the API for IM address with the IMPP API which will
simplify the transition to that one.

Reviewers: mlaurent

Reviewed By: mlaurent

Subscribers: mlaurent, kde-pim

Tags: KDE PIM

Differential Revision: https://phabricator.kde.org/D20718