Port libksieve from ktcpsocket to QSslSocket
Summary: port to QSslSocket
Test Plan: run
Reviewers: vkrause, dvratil, dfaure
Reviewed By: vkrause, dfaure
Subscribers: dfaure, kde-pim
Tags: KDE PIM
Maniphest Tasks: T11578
Differential Revision: https://phabricator.kde.org/D24047