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/proposals/map-upsert.js

@@ -0,0 +1,10 @@
+'use strict';
+// https://github.com/tc39/proposal-upsert
+require('../modules/esnext.map.emplace');
+// TODO: remove from `core-js@4`
+require('../modules/esnext.map.update-or-insert');
+// TODO: remove from `core-js@4`
+require('../modules/esnext.map.upsert');
+require('../modules/esnext.weak-map.emplace');
+// TODO: remove from `core-js@4`
+require('../modules/esnext.weak-map.upsert');