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/string-pad-webkit-bug.js

@@ -0,0 +1,5 @@
+'use strict';
+// https://github.com/zloirock/core-js/issues/280
+var userAgent = require('../internals/environment-user-agent');
+
+module.exports = /Version\/10(?:\.\d+){1,2}(?: [\w./]+)?(?: Mobile\/\w+)? Safari\//.test(userAgent);