Fix icons on Windows

KirigamiApp currently calls KIconTheme::initTheme too late for Windows,
as a workaround we can go back to calling it ourselves.

(cherry picked from commit a02a04d966)

.kde-ci.yml

@@ -10,6 +10,7 @@ Dependencies:
       'frameworks/ki18n': '@latest-kf6'
       'frameworks/kconfig': '@latest-kf6'
       'frameworks/syntax-highlighting': '@latest-kf6'
+      'frameworks/kiconthemes': '@latest-kf6'
       'frameworks/kitemmodels': '@latest-kf6'
       'frameworks/kquickcharts': '@latest-kf6'
       'frameworks/knotifications': '@latest-kf6'