Load the keyboard on-demand
Summary: No need to load the keyboard view as soon as wayland starts. It's not a simple UI and it often will be unused.
Test Plan: played with the keyboard, still worked
Reviewers: KWin, davidedmundson
Reviewed By: KWin, davidedmundson
Subscribers: davidedmundson, graesslin, kwin
Differential Revision: https://phabricator.kde.org/D22430