Deprecated KTcpSocket and KSsl* classes

Summary:
We have ported usage of those to their Qt equivalents now, so what remains
here is just the removal of all this with KF6 I think.

Reviewers: nicolasfella

Reviewed By: nicolasfella

Subscribers: kde-frameworks-devel

Tags: Frameworks

Maniphest Tasks: T11544, T11620

Differential Revision: https://phabricator.kde.org/D25237