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/is-object.js

@@ -0,0 +1,6 @@
+'use strict';
+var isCallable = require('../internals/is-callable');
+
+module.exports = function (it) {
+  return typeof it == 'object' ? it !== null : isCallable(it);
+};