Add minetest.get_game_info and allow reading game.conf (#12989)

Co-authored-by: sfan5 <sfan5@live.de>

src/script/lua_api/l_server.h

@@ -52,6 +52,9 @@ private:
 	// the returned list is sorted alphabetically for you
 	static int l_get_modnames(lua_State *L);
 
+	// get_game_info()
+	static int l_get_game_info(lua_State *L);
+
 	// print(text)
 	static int l_print(lua_State *L);