Move all remote dependencies to be local (#220)

* Experiment with javascript bundling

* Experiment with snowpack. Making progress

* Success!  Uses local js modules and assets and no cdns

* Missing local css

webroot/js/utils/chat.js

@@ -4,6 +4,7 @@ import {
   CHAT_PLACEHOLDER_OFFLINE,
 } from './constants.js';
 
+import showdown from '/js/web_modules/showdown.js';
 export function formatMessageText(message, username) {
   showdown.setFlavor('github');
   let formattedText = new showdown.Converter({