Issue #3513879 by nicxvan: Convert experimental_module_requirements_test_requirements to new Class

(cherry picked from commit 01eecd5c)

core/modules/system/tests/modules/experimental_module_requirements_test/experimental_module_requirements_test.install

-<?php
-
-/**
- * @file
- * Experimental Test Requirements module to test hook_requirements().
- */
-
-declare(strict_types=1);
-
-use Drupal\Core\Extension\Requirement\RequirementSeverity;
-
-/**
- * Implements hook_requirements().
- */
-function experimental_module_requirements_test_requirements(): array {
-  $requirements = [];
-  if (\Drupal::state()->get('experimental_module_requirements_test_requirements', FALSE)) {
-    $requirements['experimental_module_requirements_test_requirements'] = [
-      'severity' => RequirementSeverity::Error,
-      'description' => t('The Experimental Test Requirements module can not be installed.'),
-    ];
-  }
-  return $requirements;
-}

core/modules/system/tests/modules/experimental_module_requirements_test/src/Install/Requirements/ExperimentalModuleRequirementsTestRequirements.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\experimental_module_requirements_test\Install\Requirements;
+
+use Drupal\Core\Extension\InstallRequirementsInterface;
+use Drupal\Core\Extension\Requirement\RequirementSeverity;
+
+/**
+ * Install time requirements for the Experimental Requirements Test module.
+ */
+class ExperimentalModuleRequirementsTestRequirements implements InstallRequirementsInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getRequirements(): array {
+    $requirements = [];
+    if (\Drupal::state()->get('experimental_module_requirements_test_requirements', FALSE)) {
+      $requirements['experimental_module_requirements_test_requirements'] = [
+        'severity' => RequirementSeverity::Error,
+        'description' => t('The Experimental Test Requirements module can not be installed.'),
+      ];
+    }
+    return $requirements;
+  }
+
+}