[XFA] Exclude Subcategory resources from list - XF2 2.1.0

Corrected bugs

• Filters menu offered prefixes and types used only in subcategories, giving empty lists
• Category state kept in a global variable that could affect other add-ons
• PHP 8.4 deprecation notice on a method signature

New features

• Choose where subcategory resources are hidden: every category, only selected ones, or all except selected ones
• “Include subcategories” checkbox in the category filters menu, kept through sorting and pagination
• Option to turn the visitor checkbox off

Resource is compatible with XF2.3

Add-on works with XF 2.3 beta