Convert hook_form_alter implementations to OOP Hooks

Problem/Motivation

This module supports ^10 || ^11. Drupal 11.1 introduced native Object-Oriented Hooks using PHP attributes. We want to adopt this modern pattern while maintaining support for Drupal 10 and 11.0.

Proposed resolution

Implement the "Shim" pattern recommended in Drupal 11.1 OO Hooks Change Record.

1. Create Hook Class:
   • Create src/Hook/UnicodeSoftHyphensHooks.php.
   • Move the logic from unicode_soft_hyphens_form_alter to UnicodeSoftHyphensHooks::formAlter.
   • Use the #[Hook('form_alter')] attribute on the method.
   • Register this class as a service in unicode_soft_hyphens.services.yml with autowire: true (required for D10/11.0 to use it via service container, though D11.1+ discovers it automatically).
2. Update .module (Legacy Shim):
   • Keep unicode_soft_hyphens_form_alter() in the .module file.
   • Add use Drupal\Core\Hook\Attribute\LegacyHook;.
   • Add #[LegacyHook] attribute to the function. This tells Drupal 11.1+ to ignore this procedural function and use the OO Hook instead.
   • Inside the function, delegate to the service:

// @phpstan-ignore-next-line
#[LegacyHook]
function unicode_soft_hyphens_form_alter(&$form, FormStateInterface $form_state, $form_id) {
   \Drupal::service(UnicodeSoftHyphensHooks::class)->formAlter($form, $form_state, $form_id);
}