Autowiring does not support nullable types

Problem/Motivation

In #3112298: Replace REQUEST_TIME in classes with direct container access @alexpott tried to autowire a controller:

  public function __construct(
    protected ?TimeInterface $time = NULL
  ) {

TimeInterface is declared as an alias so this should work, but because the argument is nullable it did not actually work and the argument had to be explicitly autowired:

  public function __construct(
    #[Autowire(service: 'datetime.time')]
    protected ?TimeInterface $time = NULL
  ) {

Steps to reproduce

Proposed resolution

Allow nullable types to be autowired the same way as non-nullable ones.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet