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/fs-constants/README.md

@@ -0,0 +1,26 @@
+# fs-constants
+
+Small module that allows you to get the fs constants across
+Node and the browser. 
+
+```
+npm install fs-constants
+```
+
+Previously you would use `require('constants')` for this in node but that has been
+deprecated and changed to `require('fs').constants` which does not browserify.
+
+This module uses `require('constants')` in the browser and `require('fs').constants` in node to work around this
+
+
+## Usage
+
+``` js
+var constants = require('fs-constants')
+
+console.log('constants:', constants)
+```
+
+## License
+
+MIT