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/a-callable.js

@@ -0,0 +1,11 @@
+'use strict';
+var isCallable = require('../internals/is-callable');
+var tryToString = require('../internals/try-to-string');
+
+var $TypeError = TypeError;
+
+// `Assert: IsCallable(argument) is true`
+module.exports = function (argument) {
+  if (isCallable(argument)) return argument;
+  throw new $TypeError(tryToString(argument) + ' is not a function');
+};