BaguetteboxFormatter::viewElements() uses the non existing file_url_generator service

Problem/Motivation

When the module is installed on Drupal 8.9.20, it throws the following exception.

Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException: You have requested a non-existent service "file_url_generator". Did you mean one of these: "coffee.url_generator", "url_generator"? in Drupal\Component\DependencyInjection\Container->get() (line 153 of core/lib/Drupal/Component/DependencyInjection/Container.php).
Drupal::service('file_url_generator') (Line: 223)
Drupal\baguettebox\Plugin\Field\FieldFormatter\BaguetteboxFormatter->viewElements(Object, 'lv') (Line: 89)
Drupal\Core\Field\FormatterBase->view(Object, 'lv') (Line: 76)

The code needs to first check that service exists, before it uses it. If it doesn't exist, it needs to use file_url_transform_relative().