refactor: refactoring imports

将来ESMに移行しやすいように
Related: #7658

なんかmochaが起動しなくなってるけど理由不明
すぐ直したい

index.js

@@ -1,3 +1,13 @@
+/*
+import * as fs from 'fs';
+
+if (fs.existsSync('./built')) {
+	import('./built/index.js').then(built => built());
+} else {
+	console.log('Built code is not found. Probably an error occurred during a build or you just forgot to build.');
+}
+*/
+
 const fs = require('fs');
 
 if (fs.existsSync('./built')) {