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/modules/esnext.composite-symbol.js

@@ -0,0 +1,13 @@
+'use strict';
+var $ = require('../internals/export');
+var getCompositeKeyNode = require('../internals/composite-key');
+var getBuiltIn = require('../internals/get-built-in');
+var apply = require('../internals/function-apply');
+
+// https://github.com/tc39/proposal-richer-keys/tree/master/compositeKey
+$({ global: true, forced: true }, {
+  compositeSymbol: function compositeSymbol() {
+    if (arguments.length === 1 && typeof arguments[0] == 'string') return getBuiltIn('Symbol')['for'](arguments[0]);
+    return apply(getCompositeKeyNode, null, arguments).get('symbol', getBuiltIn('Symbol'));
+  }
+});