korganizer: install kontactplugins into kontact5, with JSON metadata.
Summary: This will allow kontact to use KPluginLoader one day.
Test Plan:
make uninstall, apply patch, make install, kontact loads all
3 plugins
Reviewers: winterz, mlaurent
Reviewed By: mlaurent
Subscribers: kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D28612