Port away from deprecated KWindowSystem API
Summary:
Call the all-in-one method (which handles numeric keypad better),
then split out modifiers and keycode.
Test Plan: Builds, didn't test yet.
Reviewers: zzag, graesslin, davidedmundson
Reviewed By: zzag
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D23228