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-index.js

@@ -0,0 +1,15 @@
+'use strict';
+var toIntegerOrInfinity = require('../internals/to-integer-or-infinity');
+var toLength = require('../internals/to-length');
+
+var $RangeError = RangeError;
+
+// `ToIndex` abstract operation
+// https://tc39.es/ecma262/#sec-toindex
+module.exports = function (it) {
+  if (it === undefined) return 0;
+  var number = toIntegerOrInfinity(it);
+  var length = toLength(number);
+  if (number !== length) throw new $RangeError('Wrong length or index');
+  return length;
+};