[AkonadiConsole] Port to QSortFilterProxyModel from deprecated KRecursiveFilterProxyModel
Summary:
following https://phabricator.kde.org/D25595
WARNING: don't merge this until D25595 is accepted and merged
Reviewers: dvratil, winterz
Subscribers: kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D25597