Configure MathJax to support unicode markup (#1527)

Configure MathJax to support unicode markup for format preview
to support the same unicode markup that was recently added to
the m2svg utility.

Author: mrducky4

tools/proofers/previewControl.js

@@ -177,6 +177,10 @@ window.addEventListener("DOMContentLoaded", () => {
         document.getElementById(viewMode).checked = true;
         // check if MathJax already loaded. Will break if load more than once
         if (previewStyles.allowMathPreview && typeof MathJax === "undefined") {
+            window.MathJax = {
+                loader: { load: ["input/tex", "output/svg", "[tex]/unicode"] },
+                tex: { packages: { "[+]": ["unicode"] } },
+            };
             const mathJaxScriptElement = document.createElement("script");
             mathJaxScriptElement.type = "text/javascript";
             mathJaxScriptElement.src = "https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-svg.js";