Add a feature flag for private group chats

preload.js

@@ -462,3 +462,7 @@ window.pubkeyPattern = /@[a-fA-F0-9]{64,66}\b/g;
 
 // Limited due to the proof-of-work requirement
 window.SMALL_GROUP_SIZE_LIMIT = 10;
+
+window.lokiFeatureFlags = {
+  privateGroupChats: true,
+};

ts/components/MainHeader.tsx

@@ -17,6 +17,12 @@ import { clipboard } from 'electron';
 
 import { validateNumber } from '../types/PhoneNumber';
 
+declare global {
+  interface Window {
+    lokiFeatureFlags: any;
+  }
+}
+
 interface MenuItem {
   id: string;
   name: string;
@@ -341,14 +347,17 @@ export class MainHeader extends React.Component<Props, any> {
           trigger('showAddServerDialog');
         },
       },
-      {
+    ];
+
+    if (window.lokiFeatureFlags.privateGroupChats) {
+      menuItems.push({
         id: 'createPrivateGroup',
         name: i18n('createPrivateGroup'),
         onClick: () => {
           trigger('createNewGroup');
         },
-      },
-    ];
+      });
+    }
 
     const passItem = (type: string) => ({
       id: `${type}Password`,