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/to-indexed-object.js

@@ -0,0 +1,8 @@
+'use strict';
+// toObject with fallback for non-array-like ES3 strings
+var IndexedObject = require('../internals/indexed-object');
+var requireObjectCoercible = require('../internals/require-object-coercible');
+
+module.exports = function (it) {
+  return IndexedObject(requireObjectCoercible(it));
+};