Use cjs for node-main-setup so it works in bun as well as node. (mathjax/MathJax#3476)

Author: dpvc

components/mjs/node-main/config.json

@@ -5,7 +5,7 @@
     "copy": [
       "node-main.mjs",
       "node-main.cjs",
-      "node-main-setup.mjs"
+      "node-main-setup.cjs"
     ]
   },
   "webpack": {

components/mjs/node-main/node-main-setup.cjs

@@ -0,0 +1,5 @@
+global.require = require;
+const path = require("path");
+
+if (!global.MathJax) global.MathJax = {};
+global.MathJax.__dirname = __dirname;

components/mjs/node-main/node-main-setup.mjs

@@ -1,4 +1,4 @@
-import './node-main-setup.mjs';
+import './node-main-setup.cjs';
 import {MathJax} from './node-main.js';
 export default MathJax;
 export const init = MathJax.init;