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/components/chat/message.js

@@ -1,5 +1,5 @@
-import { h, Component } from 'https://unpkg.com/preact?module';
-import htm from 'https://unpkg.com/htm?module';
+import { h, Component } from '/js/web_modules/preact.js';
+import htm from '/js/web_modules/htm.js';
 const html = htm.bind(h);
 
 import { messageBubbleColorForString } from '../../utils/user-colors.js';