Bug: router service adds backslash to controllername if route is configured

[chriseilander]

Describe the bug
When a route isn't defined, the controllerName() function in service('router') returns an expected string like 'App\Controllers{controllername}'. But when a route is defined in the routes.php it also returns an extra \ like '\App\Controllers{controllername}'.

CodeIgniter 4 version
CodeIgniter 4 RC 3 zip version
CodeIgniter 4 Dev starter composer
CodeIgniter 4 App starter composer

Affected module(s)
Probably the router service

Expected behavior, and steps to reproduce if appropriate
Let the namespace define the route, and return the controller name using
$router = service("router"); echo $router->controllerName();
It should return the namespace of the controller with the name.

Now define the route in routes.php, and the same code will return an \ with the namespace of the controller with the controllername.

I expected them to be the same.

[samsonasik]

@chriseilander @MGatner I think the correct one is the one with \ prefix as it fqcn like in the doc comment at https://github.com/codeigniter4/CodeIgniter4/pull/2734/files#diff-d2374d65fd714c18dbee9f5adaa8dd6cL552.

I created PR #2734 for it.