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/@react-native/js-polyfills/README.md

@@ -0,0 +1,21 @@
+# @react-native/js-polyfills
+
+[![Version][version-badge]][package]
+
+## Installation
+
+```
+yarn add @react-native/js-polyfills
+```
+
+*Note: We're using `yarn` to install deps. Feel free to change commands to use `npm` 3+ and `npx` if you like*
+
+[version-badge]: https://img.shields.io/npm/v/@react-native/js-polyfills?style=flat-square
+[package]: https://www.npmjs.com/package/@react-native/js-polyfills
+
+## Testing
+
+To run the tests in this package, run the following commands from the React Native root folder:
+
+1. `yarn` to install the dependencies. You just need to run this once
+2. `yarn jest packages/polyfills`.