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/core-js/internals/define-built-ins.js

@@ -0,0 +1,7 @@
+'use strict';
+var defineBuiltIn = require('../internals/define-built-in');
+
+module.exports = function (target, src, options) {
+  for (var key in src) defineBuiltIn(target, key, src[key], options);
+  return target;
+};