Feature: [UI] Split AI/Game Script configuration windows and add them to world gen window (#10058)

src/widgets/intro_widget.h

@@ -32,6 +32,7 @@ enum SelectGameIntroWidgets {
 	WID_SGI_GRF_SETTINGS,          ///< NewGRF button.
 	WID_SGI_CONTENT_DOWNLOAD,      ///< Content Download button.
 	WID_SGI_AI_SETTINGS,           ///< AI button.
+	WID_SGI_GS_SETTINGS,           ///< Game Script button.
 	WID_SGI_EXIT,                  ///< Exit button.
 };