Handle deprecated function file_icon_class

It seems that phpstan is going to complain about missing classes or functions, but ultimately we cannot squelch that. The function was removed in 11, but the IconMimeType class does not exist until 10.3 so the pipeline warnings will persist.

Ultimately, this should work for all 3 versions:

      if (!class_exists(DeprecationHelper::class)) {
        $icon_class = file_icon_class($mime_type);
      }
      else {
        $icon_class = DeprecationHelper::backwardsCompatibleCall(
          \Drupal::VERSION,
          '10.3',
          static fn () => IconMimeTypes::getIconClass($mime_type),
          static fn () => file_icon_class($mime_type)
        );
      }

      $url_options['attributes'] = [
        'type' => "$mime_type; length={$file->getSize()}",
        'title' => $filename,
        // Classes to add to the file field for icons.
        'class' => [
          'file',
          // Add a specific class for each and every mime type.
          'file--mime-' . strtr($mime_type, ['/' => '-', '.' => '-']),
          // Add a more general class for groups of well known MIME types.
          'file--' . $icon_class,
        ],
      ];

Automatically closed - issue fixed for 2 weeks with no activity.