Use WhatsThis strings for tooltips in Konfigurator window

Summary:
Some might want the tooltips on hover.

BUG: 390988

Test Plan: Compile, install, should show tooltips in Konfigurator window on hover.

Reviewers: #krusader, gengisdave

Reviewed By: #krusader, gengisdave

Subscribers: gengisdave

Differential Revision: https://phabricator.kde.org/D29398