fix: declare $optionCollection property to silence PHP 8.2 dynamic-property deprecation

$optionCollection was used as a lazy-loaded per-attribute-id cache in
loadOptionCollection() but was never declared as a class property.
PHP 8.2 deprecated dynamic property creation; Magento's strict error
handler promotes that deprecation to an exception, causing exit code 1
in CI. Declare it as `private array $optionCollection = []`.

Author: chevli

Component/Attributes.php

@@ -59,6 +59,8 @@ class Attributes implements ComponentInterface
 
     protected array $swatchMap = [];
 
+    private array $optionCollection = [];
+
     public function __construct(
         protected readonly EavSetup $eavSetup,
         protected readonly AttributeRepositoryInterface $attributeRepository,