Drupal 11.4: "Undefined array key #item_attributes" in EasyLqpImagesFormatte

Problem/Motivation

Drupal 11.4 renamed the #item_attributes render array key produced by
ImageFormatter::viewElements() to #attributes. The key is deprecated
in 11.4 and removed in 12.0 (see change record
3554585).

EasyLqpImagesFormatter extends ImageFormatter and reads
$elements[$delta]['#item_attributes'] at line 175. On Drupal 11.4 that key no
longer exists, which produces two PHP warnings per rendered image:

Warning: Undefined array key "#item_attributes" in
Drupal\easy_lqp\Plugin\Field\FieldFormatter\EasyLqpImagesFormatter->viewElements()
(line 175 of modules/contrib/easy_lqp/src/Plugin/Field/FieldFormatter/EasyLqpImagesFormatter.php)

Warning: foreach() argument must be of type array|object, null given in
Drupal\Core\Template\Attribute->__construct()
(line 89 of core/lib/Drupal/Core/Template/Attribute.php)

The missing key yields NULL, which is passed to new Attribute(NULL), whose
constructor then foreaches over NULL — hence the second warning.

Two consequences:

• Drupal logs both warnings on every image render. On a page rendering 32 images that is 64
  watchdog entries per request, which quickly evicts everything else under the default
  dblog row limit of 1000.
• The loading attribute set by ImageFormatter is silently lost,
  because the Attribute object is constructed empty. Verified on a page with 32
  easy_lqp images: 0 of 32 carried loading= on 11.4, and 32 of 32 did after the
  fix.

Steps to reproduce

1. Install Drupal 11.4 (tested on 11.4.4) with easy_lqp 2.0.2 on PHP 8.4.
2. Configure an image field display to use the "Easy LQP images" formatter.
3. View a page rendering that field with error display enabled.
4. Two warnings appear per image; they are also written to dblog regardless of
   the error display setting.

Proposed resolution

Read #attributes first and fall back to #item_attributes, so the
formatter works on both Drupal 10/11.3 and 11.4+:

$item_attributes = $elements[$delta]['#attributes']
  ?? $elements[$delta]['#item_attributes']
  ?? [];
$elements[$delta]['#item_attributes'] = new Attribute($item_attributes);

The module keeps writing to #item_attributes because that is the variable its
own easy_lqp_formatter theme hook declares and its template renders. Renaming the
module's own theme variable would be a separate, template-breaking change and is not proposed
here.

Remaining tasks

• Review the merge request
• Commit and tag a release

User interface changes

None.

API changes

None.

Data model changes

None.