shifted inclusion of katex CSS to webpack.config.json in element-web

Author: akissinger

src/HtmlUtils.tsx

@@ -27,7 +27,6 @@ import classNames from 'classnames';
 import EMOJIBASE_REGEX from 'emojibase-regex';
 import url from 'url';
 import katex from 'katex';
-import 'katex/dist/katex.min.css';
 import { AllHtmlEntities } from 'html-entities';
 import SdkConfig from './SdkConfig';