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/an-object.js

@@ -0,0 +1,11 @@
+'use strict';
+var isObject = require('../internals/is-object');
+
+var $String = String;
+var $TypeError = TypeError;
+
+// `Assert: Type(argument) is Object`
+module.exports = function (argument) {
+  if (isObject(argument)) return argument;
+  throw new $TypeError($String(argument) + ' is not an object');
+};