task: #3584297 Move alterEntityForm() from DomainPathHelper to DomainPathFormHooks

Frank Mablyrequested to merge
issue/domain_path-3584297:3584297-move-alterentityform-from into 3.x

Move alterEntityForm(), afterEntityFormBuild(), validateEntityForm(), and submitEntityForm() from DomainPathHelper to DomainPathFormHooks.

Form callbacks are static to avoid service serialization into the form cache. submitEntityForm() delegates to an instance method via \Drupal::service() since it needs EntityTypeManagerInterface. afterEntityFormBuild() and validateEntityForm() are pure static (no service dependencies).

Closes #3584297

Merge request reports