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/is-symbol.js

@@ -0,0 +1,14 @@
+'use strict';
+var getBuiltIn = require('../internals/get-built-in');
+var isCallable = require('../internals/is-callable');
+var isPrototypeOf = require('../internals/object-is-prototype-of');
+var USE_SYMBOL_AS_UID = require('../internals/use-symbol-as-uid');
+
+var $Object = Object;
+
+module.exports = USE_SYMBOL_AS_UID ? function (it) {
+  return typeof it == 'symbol';
+} : function (it) {
+  var $Symbol = getBuiltIn('Symbol');
+  return isCallable($Symbol) && isPrototypeOf($Symbol.prototype, $Object(it));
+};