Replace deprecated method getName

Problem/Motivation

The method ModuleHandler::getName() is deprecated in Drupal 10.3.0 and will be removed in Drupal 11.0.0.


The AdminForm class currently uses this method, triggering deprecation warnings.

See change record: https://www.drupal.org/node/3310017 (related to extension list transition).

Proposed resolution

1. Inject the extension.list.module service into \Drupal\mailsystem\Form\AdminForm.


2. Replace usages of $this->moduleHandler->getName($module) with $this->moduleExtensionList->getName($module).