Fix return types and baselined errors of core/tests/ Kernel code - round 5

rebased and added types to base class properties and some of the traits

anyone willing tackle #7 and split this up, feel free.

#12 yes, that solves this baseline entry:

$ignoreErrors[] = [
	'message' => '#^Parameter \\#2 \\$language_manager of class Drupal\\\\locale\\\\LocaleDefaultConfigStorage constructor expects Drupal\\\\language\\\\ConfigurableLanguageManagerInterface, Drupal\\\\Core\\\\Language\\\\LanguageManagerInterface given\\.$#',
	'identifier' => 'argument.type',
	'count' => 1,
	'path' => __DIR__ . '/modules/locale/tests/src/Kernel/LocaleDefaultConfigStorageTest.php',
];

That happens because \Drupal has this

  /**
   * Returns the language manager service.
   *
   * @return \Drupal\Core\Language\LanguageManagerInterface
   *   The language manager.
   */
  public static function languageManager() {
    return static::getContainer()->get('language_manager');
  }

while Drupal\locale\LocaleDefaultConfigStorage expects

  /**
   * Constructs a LocaleDefaultConfigStorage.
   *
   * @param \Drupal\Core\Config\StorageInterface $config_storage
   *   The storage object to use for reading configuration data.
   * @param \Drupal\language\ConfigurableLanguageManagerInterface $language_manager
   *   The language manager.
   * @param string $install_profile
   *   The current installation profile.
   */
  public function __construct(StorageInterface $config_storage, ConfigurableLanguageManagerInterface $language_manager, $install_profile) {
    $this->configStorage = $config_storage;
    $this->languageManager = $language_manager;

    $this->requiredInstallStorage = new ExtensionInstallStorage($this->configStorage, ExtensionInstallStorage::CONFIG_INSTALL_DIRECTORY, ExtensionInstallStorage::DEFAULT_COLLECTION, TRUE, $install_profile);
    $this->optionalInstallStorage = new ExtensionInstallStorage($this->configStorage, ExtensionInstallStorage::CONFIG_OPTIONAL_DIRECTORY, ExtensionInstallStorage::DEFAULT_COLLECTION, TRUE, $install_profile);
  }

in fact I think \Drupal is wrong (otherwise we would get a TypeError, as the parameter is strictly typed in the constructor), but I did not want to change \Drupal, here it's only about test code. Splitting the code in a variable assignment and asserting the inheritance on the variable makes PHPStan be confident we are not passing a wrongly typed parameter.

Please, add comments inline on the MR if possible, it's easier to see the context.

Actually - checked a bit.

\Drupal is right. Drupal\Core\Language\LanguageManagerInterface is an ancestor of the Drupal\language\ConfigurableLanguageManager, that implements the additional Drupal\language\ConfigurableLanguageManagerInterface interface.

So it's right that \Drupal::languageManager() returns the topmost interface. The language module then overrides the standard manager with its own class, so the concrete class returned will be the replaced one that implements both interfaces.

But since Drupal\locale\LocaleDefaultConfigStorage requires ConfigurableLanguageManagerInterface the assertInstanceOf is IMHO the proper 'type narrowing' action to take.

#16 if it's OK to change runtime code in this MR, sure we can, done in latest commit.