New service to make updating configuration entities easier inside update hooks

We have a large number of updates that do something for a group of configuration entities of a particular type. All of these functions should use the batch system because generally there are n amount of configuration entities present.

It will also reduce the amount of boilerplate code that is needed to run these updates, since all follow the same general pattern. Using a standardised way of running these updates will help reduce the chance of little mistakes getting into this boilerplate code.

Before:

function views_post_update_table_display_cache_max_age(&$sandbox = NULL) {
  $storage = \Drupal::entityTypeManager()->getStorage('view');
  if (!isset($sandbox['views'])) {
    $sandbox['views'] = $storage->getQuery()->accessCheck(FALSE)->execute();
    $sandbox['count'] = count($sandbox['views']);
  }

  for ($i = 0; $i < 10 && count($sandbox['views']); $i++) {
    $view_id = array_shift($sandbox['views']);
    if ($view = $storage->load($view_id)) {
      $displays = $view->get('display');
      foreach ($displays as $display_name => &$display) {
        if (isset($display['display_options']['style']['type']) && $display['display_options']['style']['type'] === 'table') {
          $view->save();
        }
      }
    }
  }

  $sandbox['#finished'] = empty($sandbox['views']) ? 1 : ($sandbox['count'] - count($sandbox['views'])) / $sandbox['count'];
}

After:

function views_post_update_table_display_cache_max_age(&$sandbox = NULL) {
  \Drupal::classResolver(ConfigEntityUpdater::class)->update($sandbox, 'view', function ($view) {
    /** @var \Drupal\views\ViewEntityInterface $view */
    $displays = $view->get('display');
    foreach ($displays as $display_name => &$display) {
      if (isset($display['display_options']['style']['type']) && $display['display_options']['style']['type'] === 'table') {
        return TRUE;
      }
    }
    return FALSE;
  });
}

The new service has one method update that takes the batch $sandbox, the config entity type, and a callback that evaluates if the config entity needs to be saved. This callback can also be used to make any needed changes to the entity.