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/function-uncurry-this-clause.js

@@ -0,0 +1,10 @@
+'use strict';
+var classofRaw = require('../internals/classof-raw');
+var uncurryThis = require('../internals/function-uncurry-this');
+
+module.exports = function (fn) {
+  // Nashorn bug:
+  //   https://github.com/zloirock/core-js/issues/1128
+  //   https://github.com/zloirock/core-js/issues/1130
+  if (classofRaw(fn) === 'Function') return uncurryThis(fn);
+};