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/new-promise-capability.js

@@ -0,0 +1,21 @@
+'use strict';
+var aCallable = require('../internals/a-callable');
+
+var $TypeError = TypeError;
+
+var PromiseCapability = function (C) {
+  var resolve, reject;
+  this.promise = new C(function ($$resolve, $$reject) {
+    if (resolve !== undefined || reject !== undefined) throw new $TypeError('Bad Promise constructor');
+    resolve = $$resolve;
+    reject = $$reject;
+  });
+  this.resolve = aCallable(resolve);
+  this.reject = aCallable(reject);
+};
+
+// `NewPromiseCapability` abstract operation
+// https://tc39.es/ecma262/#sec-newpromisecapability
+module.exports.f = function (C) {
+  return new PromiseCapability(C);
+};