Add IM protocol information and protocol listing
Summary:
This is largely coming from akonadi-contacts IMProtocol's class, but
adjusted to be more in line with the RFC 4770 format. Non-static methods
for this are to follow.
Reviewers: mlaurent
Reviewed By: mlaurent
Subscribers: kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D20705