Show application icon in Plasma Wayland sessions

kwin_wayland fetches application icons from .desktop files, so we
need to set the desktop filename on the QGuiApplication instance
(otherwise kwin will set a generic wayland icon as fallback).

Change-Id: I89921ace4a5a4ff2a2387111e51a8914f58e44a8
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/app/main.cpp

@@ -523,6 +523,8 @@ int main(int argc, char **argv)
         }
     }
 
+    app.setDesktopFileName("org.qt-project.qtcreator.desktop");
+
     // Make sure we honor the system's proxy settings
     QNetworkProxyFactory::setUseSystemConfiguration(true);