KCM/Kwinoptions: Port title bar and window actions tabs UI and conf to KConfigXT

Summary: Depends on D27463

Reviewers: crossi, bport, ervin, #kwin, zzag

Reviewed By: ervin, #kwin, zzag

Subscribers: zzag, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D27477