FRE-600: Fix code review blockers

- Consolidated duplicate UndoManagers to single instance
- Fixed connection promise to only resolve on 'connected' status
- Fixed WebSocketProvider import (WebsocketProvider)
- Added proper doc.destroy() cleanup
- Renamed isPresenceInitialized property to avoid conflict

Co-Authored-By: Paperclip <noreply@paperclip.ing>

node_modules/is-html/index.js

@@ -0,0 +1,7 @@
+'use strict';
+const htmlTags = require('html-tags');
+
+const basic = /\s?<!doctype html>|(<html\b[^>]*>|<body\b[^>]*>|<x-[^>]+>)+/i;
+const full = new RegExp(htmlTags.map(tag => `<${tag}\\b[^>]*>`).join('|'), 'i');
+
+module.exports = string => basic.test(string) || full.test(string);