DEV: Correct typos and spelling mistakes (#12812)

Over the years we accrued many spelling mistakes in the code base. 

This PR attempts to fix spelling mistakes and typos in all areas of the code that are extremely safe to change 

- comments
- test descriptions
- other low risk areas

lib/javascripts/widget-hbs-compiler.js

@@ -125,7 +125,7 @@ function mustacheValue(node, state) {
       return `${useHelper(state, "iconNode")}(${valueOf(node.params[0])})`;
       break;
     default:
-      // Shortcut: If our mustach has hash arguments, we can assume it's attaching.
+      // Shortcut: If our mustache has hash arguments, we can assume it's attaching.
       // For example `{{home-logo count=123}}` can become `this.attach('home-logo, { "count": 123 });`
       let hash = node.hash;
       if (hash.pairs.length) {