Backport PR jupyter#5934: Add shim to mathjaxutils.js

Author: Zsailer

notebook/static/notebook/js/mathjaxutils.js

@@ -0,0 +1,8 @@
+
+define([
+    'base/js/mathjaxutils'
+], function(mathjaxutils) {
+    "use strict"
+
+    return mathjaxutils;
+});