Migrate app to TypeScript (#1637)

* Initial setup and migrated src/common

* WIP

* WIP

* WIP

* Main module basically finished

* Renderer process migrated

* Added CI step and some fixes

* Fixed remainder of issues and added proper ESLint config

* Fixed a couple issues

* Progress!

* Some more fixes

* Fixed a test

* Fix build step

* PR feedback

src/renderer/modals/urlView/urlView.tsx

@@ -0,0 +1,23 @@
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+import 'renderer/css/components/HoveringURL.css';
+
+const queryString = window.location.search;
+const urlParams = new URLSearchParams(queryString);
+
+import React from 'react';
+import ReactDOM from 'react-dom';
+
+import UrlDescription from '../../components/urlDescription';
+
+const start = async () => {
+    ReactDOM.render(
+        <UrlDescription
+            url={decodeURIComponent(urlParams.get('url')!)}
+        />,
+        document.getElementById('app'),
+    );
+};
+
+start();