✨ optimize location info gen in codegen

and refactor lib.nas, add multiple native modules

src/ast_visitor.cpp

@@ -10,10 +10,6 @@ bool ast_visitor::visit_call(call* node) {
     return true;
 }
 
-bool ast_visitor::visit_file_info(file_info* node) {
-    return true;
-}
-
 bool ast_visitor::visit_null_expr(null_expr* node) {
     return true;
 }