Messenger example - reset authenticated channel

• Add ResetAuthFeature library to xx-messenger example.
• Implement resetting authenticated channel with provided contact.
• Fix reset auth callback handler in xx-messenger example.

Examples/xx-messenger/Sources/AppCore/AuthCallbackHandler/AuthCallbackHandlerReset.swift

@@ -18,7 +18,7 @@ extension AuthCallbackHandlerReset {
       guard var dbContact = try db().fetchContacts(.init(id: [id])).first else {
         return
       }
-      dbContact.authStatus = .stranger
+      dbContact.authStatus = .friend
       dbContact = try db().saveContact(dbContact)
     }
   }