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/modules/es.object.is-extensible.js

@@ -0,0 +1,10 @@
+'use strict';
+var $ = require('../internals/export');
+var $isExtensible = require('../internals/object-is-extensible');
+
+// `Object.isExtensible` method
+// https://tc39.es/ecma262/#sec-object.isextensible
+// eslint-disable-next-line es/no-object-isextensible -- safe
+$({ target: 'Object', stat: true, forced: Object.isExtensible !== $isExtensible }, {
+  isExtensible: $isExtensible
+});