Provide service aliases for autowiring

Problem/Motivation

Drupal has been expanding its support of services that can have their arguments autowired. One exciting new example of this is the ability to use object-oriented hooks in Drupal 11.

When adding the externalauth.authmap service to an autowired hook class, I ran into this error:
Cannot autowire service "Drupal\custom_module\Hook\MyCustomHooks": argument "$authmap" of method "__construct()" references interface "Drupal\externalauth\AuthmapInterface" but no such service exists. You should maybe alias this interface to the existing "externalauth.authmap" service.

Steps to reproduce

1. Create a class with a hook following the documentation here → .
2. Add a services.yml file for your hook class and include autowire: true
3. Make sure to include a construct method for your class as shown below and observe the error message:

<?php

namespace Drupal\custom_module\Hook;

use Drupal\externalauth\AuthmapInterface;

class MyCustomHooks {

  public function __construct(
    private AuthmapInterface $authmap,
  ) {}

...
}

Proposed resolution

Create aliases for externalauth.authmap and externalauth.externalauth in externalauth.services.yml.