Revert to using our own drag-move code for wxGTK wxMiniFrame with non-Wayland backends

At least one WM (KDE's KWin) does not generate X11 configure events when dragging
a window using gtk_window_begin_move_drag(). We need the configure events so we
can generate wxMoveEvent, which AUI needs in order to re-attach a floating pane.
This is functionally a revert of b8789b9d6f for backends other than Wayland.
See #18372 #18669

include/wx/gtk/minifram.h

@@ -52,6 +52,10 @@ protected:
 
  // implementation
 public:
+#ifndef __WXGTK4__
+    bool m_isDragMove;
+    wxSize m_dragOffset;
+#endif
     wxBitmap  m_closeButton;
     int m_miniEdge;
     int m_miniTitle;