fix: allow null user type in setuser methods and improve type hinting

This commit includes changes made to both the Article.php and ArticleList.php classes in the QUI\ERP\Accounting directory. The setUser methods now accept a null type for the 'User' parameter, giving more flexibility when calculating user details.

Type hinting was also improved in the ArticleList class. The variable type indicators were changed from 'int|float' to 'int | float', and from 'Factor|QUI\ERP\Products\Utils\PriceFactor' to 'Factor | QUI\ERP\Products\Utils\PriceFactor', improving readability and clarity of code.

Lastly, the 'template' and 'articleTemplate' parameters in the 'toHTMLWithCSS' method now support both 'bool' and 'string' types, adding flexibility to template usage.

src/QUI/ERP/Accounting/Article.php

@@ -499,9 +499,9 @@ public function getUser(): ?QUI\Interfaces\Users\User
     /**
      * Set the user to the product, this user will be used for the calculation
      *
-     * @param QUI\Interfaces\Users\User $User
+     * @param null|QUI\Interfaces\Users\User $User
      */
-    public function setUser(QUI\Interfaces\Users\User $User): void
+    public function setUser(null | QUI\Interfaces\Users\User $User): void
     {
         $this->calculated = false;
         $this->User = $User;