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/object-keys.js

@@ -0,0 +1,10 @@
+'use strict';
+var internalObjectKeys = require('../internals/object-keys-internal');
+var enumBugKeys = require('../internals/enum-bug-keys');
+
+// `Object.keys` method
+// https://tc39.es/ecma262/#sec-object.keys
+// eslint-disable-next-line es/no-object-keys -- safe
+module.exports = Object.keys || function keys(O) {
+  return internalObjectKeys(O, enumBugKeys);
+};