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/mutation.js

@@ -0,0 +1,22 @@
+'use strict';
+//based off rsvp https://github.com/tildeio/rsvp.js
+//license https://github.com/tildeio/rsvp.js/blob/master/LICENSE
+//https://github.com/tildeio/rsvp.js/blob/master/lib/rsvp/asap.js
+
+var Mutation = global.MutationObserver || global.WebKitMutationObserver;
+
+exports.test = function () {
+  return Mutation;
+};
+
+exports.install = function (handle) {
+  var called = 0;
+  var observer = new Mutation(handle);
+  var element = global.document.createTextNode('');
+  observer.observe(element, {
+    characterData: true
+  });
+  return function () {
+    element.data = (called = ++called % 2);
+  };
+};