How to add names for routes in groups

## Describe the bug

This works:
```php
app()->get('/', ['name' => 'home', function () {
    render('index');
}]);
```

And this doesn't work:
```php
app()->group('/admin', ['name' => 'admin', function () {
    app()->resource('/users', 'UsersController');
}]);
```

## Expected behavior

I want to get routes such like these:
- `admin.users.index`
- `admin.users.create`
- etc

