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/immediate/lib/stateChange.js

@@ -0,0 +1,24 @@
+'use strict';
+
+exports.test = function () {
+  return 'document' in global && 'onreadystatechange' in global.document.createElement('script');
+};
+
+exports.install = function (handle) {
+  return function () {
+
+    // Create a <script> element; its readystatechange event will be fired asynchronously once it is inserted
+    // into the document. Do so, thus queuing up the task. Remember to clean up once it's been called.
+    var scriptEl = global.document.createElement('script');
+    scriptEl.onreadystatechange = function () {
+      handle();
+
+      scriptEl.onreadystatechange = null;
+      scriptEl.parentNode.removeChild(scriptEl);
+      scriptEl = null;
+    };
+    global.document.documentElement.appendChild(scriptEl);
+
+    return handle;
+  };
+};