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/regexp-get-flags.js

@@ -0,0 +1,16 @@
+'use strict';
+var call = require('../internals/function-call');
+var hasOwn = require('../internals/has-own-property');
+var isPrototypeOf = require('../internals/object-is-prototype-of');
+var regExpFlagsDetection = require('../internals/regexp-flags-detection');
+var regExpFlagsGetterImplementation = require('../internals/regexp-flags');
+
+var RegExpPrototype = RegExp.prototype;
+
+module.exports = regExpFlagsDetection.correct ? function (it) {
+  return it.flags;
+} : function (it) {
+  return (!regExpFlagsDetection.correct && isPrototypeOf(RegExpPrototype, it) && !hasOwn(it, 'flags'))
+    ? call(regExpFlagsGetterImplementation, it)
+    : it.flags;
+};