Use certificate handling code for both SSL and TLS

Summary: The initial certificate handling code has been implemented for TLS only. Since it works for SSL as well and may be required in some scenarious, use the code whenever any security protocol is configured.

Reviewers: mlaurent

Reviewed By: mlaurent

Subscribers: knauss, kde-pim

Tags: #kde_pim

Differential Revision: https://phabricator.kde.org/D28915