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/a-set.js

@@ -0,0 +1,8 @@
+'use strict';
+var has = require('../internals/set-helpers').has;
+
+// Perform ? RequireInternalSlot(M, [[SetData]])
+module.exports = function (it) {
+  has(it);
+  return it;
+};