Move window XID properties to X11Window

Scripts can't use platform specific apis so it makes little sense to
have these properties. On the other hand, they can be useful for debug
console.

src/window.h

@@ -79,8 +79,6 @@ class KWIN_EXPORT Window : public QObject
 {
     Q_OBJECT
 
-    Q_PROPERTY(qulonglong frameId READ frameId)
-
     /**
      * This property holds rectangle that the pixmap or buffer of this Window
      * occupies on the screen. This rectangle includes invisible portions of the
@@ -131,8 +129,6 @@ class KWIN_EXPORT Window : public QObject
      */
     Q_PROPERTY(KWin::Output *output READ output NOTIFY screenChanged)
 
-    Q_PROPERTY(qulonglong windowId READ window CONSTANT)
-
     Q_PROPERTY(QRectF rect READ rect)
     Q_PROPERTY(QPointF clientPos READ clientPos)
     Q_PROPERTY(QSizeF clientSize READ clientSize)

src/x11window.h

@@ -92,6 +92,8 @@ class KWIN_EXPORT X11Window : public Window
      * Only GTK+ are detected.
      */
     Q_PROPERTY(bool clientSideDecorated READ isClientSideDecorated NOTIFY clientSideDecoratedChanged)
+    Q_PROPERTY(qulonglong frameId READ frameId CONSTANT)
+    Q_PROPERTY(qulonglong windowId READ window CONSTANT)
 public:
     explicit X11Window();
     ~X11Window() override; ///< Use destroyWindow() or releaseWindow()