Fatal error: Type of ImageFieldTokensFormatter::$currentUser must be AccountInterface on Drupal 11.4

Problem/Motivation

After updating Drupal core to 11.4, every page that renders an image field
using the "Image Field Tokens" formatter fails with a WSOD / HTTP 500:

PHP Fatal error: Type of
Drupal\imagefield_tokens\Plugin\Field\FieldFormatter\ImageFieldTokensFormatter::$currentUser
must be Drupal\Core\Session\AccountInterface (as in class
Drupal\image\Plugin\Field\FieldFormatter\ImageFormatter) in
web/modules/contrib/imagefield_tokens/src/Plugin/Field/FieldFormatter/ImageFieldTokensFormatter.php
on line 34

`ImageFieldTokensFormatter` re-declares two properties that are inherited
from core's `ImageFormatter`:

/**
 * The current user.
 *
 * @var \Drupal\Core\Session\AccountInterface
 */
protected $currentUser;

/**
 * The image style entity storage.
 *
 * @var \Drupal\image\ImageStyleStorageInterface
 */
protected $imageStyleStorage;

Drupal 11.4 added native type declarations to these properties in core's
`ImageFormatter`. Since PHP property types are invariant, the untyped
re-declarations in the child class now cause a fatal error as soon as the
class is loaded. The fatal is currently reported for `$currentUser`; once
that is fixed, `$imageStyleStorage` will trigger the same error.

Steps to reproduce

1. Install Drupal core 11.4 with imagefield_tokens 3.2.0
2. Configure an image field on any content type to use the
   "Image Field Tokens" formatter on Manage display.
3. Visit a page that renders this field.
4. HTTP 500 with the fatal error above.

Proposed resolution

Remove both redundant property declarations from
`ImageFieldTokensFormatter`. They are inherited from the parent class and
are already assigned via `parent::__construct()`, so no other changes are
required.

Because the properties are removed rather than typed, the fix remains
backwards compatible with Drupal 11.3 and 10.x.

Remaining tasks

• Review MR.
• Commit and tag a new release.