[client] wayland: improve fractional scale protocol compatibility

There is no reason to call a bunch of stuff before the xdg_surface is
configured, so let's not call them and cause early painting to happen
should the compositor decide to send the `preferred_scale` message early.

client/displayservers/Wayland/interface/desktop.h

@@ -58,6 +58,8 @@ typedef struct WL_DesktopOps
   bool (*pollInit)(struct wl_display * display);
 
   void (*pollWait)(struct wl_display * display, int epollFd, unsigned int time);
+
+  bool (*configured)(void);
 }
 WL_DesktopOps;