Add mechanism to override setting names used in config file

src/settings_internal.h

@@ -77,12 +77,15 @@ enum SettingType {
 enum SettingOnGuiCtrlType {
 	SOGCT_DESCRIPTION_TEXT,   ///< Description text callback
 	SOGCT_GUI_DROPDOWN_ORDER, ///< SF_GUI_DROPDOWN reordering callback
+	SOGCT_CFG_NAME,           ///< Config file name override
+	SOGCT_CFG_FALLBACK_NAME,  ///< Config file name within group fallback
 };
 
 struct SettingOnGuiCtrlData {
 	SettingOnGuiCtrlType type;
 	StringID text;
 	int val;
+	const char *str = nullptr;
 };
 
 struct IniItem;