[kcmkwin/options] Improve the look of the KWin options KCM UIs
Summary:
Apply the KDE HIG, use form layouts, make desktop files consistent and make the KCMs look better.
Test Plan: Open the Window Behavior KCMs. All options should still work
Reviewers: KWin, Plasma, VDG, ngraham, zzag
Reviewed By: KWin, Plasma, VDG, ngraham, zzag
Subscribers: ngraham, davidedmundson, zzag, VDG, Plasma, kwin, KWin
Tags: KWin
Maniphest Tasks: T10273
Differential Revision: https://phabricator.kde.org/D23615