Use node prefix for build-in modules (#3340)

It is basically a cosmetic thing, but has the following advantages:

1. Consistency with the official node documentation. The prefix is used
there.
2. It is easier to recognize the build-in modules.

js/app.js

@@ -8,8 +8,8 @@
 // Alias modules mentioned in package.js under _moduleAliases.
 require("module-alias/register");
 
-const fs = require("fs");
-const path = require("path");
+const fs = require("node:fs");
+const path = require("node:path");
 const envsub = require("envsub");
 const Log = require("logger");