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/utils-merge/index.js

@@ -0,0 +1,23 @@
+/**
+ * Merge object b with object a.
+ *
+ *     var a = { foo: 'bar' }
+ *       , b = { bar: 'baz' };
+ *
+ *     merge(a, b);
+ *     // => { foo: 'bar', bar: 'baz' }
+ *
+ * @param {Object} a
+ * @param {Object} b
+ * @return {Object}
+ * @api public
+ */
+
+exports = module.exports = function(a, b){
+  if (a && b) {
+    for (var key in b) {
+      a[key] = b[key];
+    }
+  }
+  return a;
+};