Fix - Check method existence before calling uninstall on custom assets

[RomainLvr]

Checklist before requesting a review

Please delete options that are not relevant.

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• This change requires a documentation update.

Description

• Here is a brief description of what this PR does

Problem:
After migrating to GLPI 11, uninstalling the GenericObject plugin fails with UndefinedMethodError when trying to call uninstall() on Custom Asset classes that don't have this method.

[2025-11-10 10:35:42] glpi.CRITICAL:   *** Uncaught PHP Exception Symfony\Component\ErrorHandler\Error\UndefinedMethodError: "Attempted to call an undefined method named "uninstall" of class "Glpi\CustomAsset\inventaireAsset"." at hook.php line 95
  Backtrace :
  ./marketplace/genericobject/hook.php:95            
  ./src/Plugin.php:1095                              plugin_genericobject_uninstall()
  :                                                  Plugin->uninstall()
  ./src/Glpi/Marketplace/Controller.php:670          call_user_func()
  ./src/Glpi/Marketplace/Controller.php:577          Glpi\Marketplace\Controller->setPluginState()
  ./ajax/marketplace.php:66                          Glpi\Marketplace\Controller->uninstallPlugin()
  ...Glpi/Controller/LegacyFileLoadController.php:64 require()
  ./vendor/symfony/http-kernel/HttpKernel.php:181    Glpi\Controller\LegacyFileLoadController->__invoke()
  ./vendor/symfony/http-kernel/HttpKernel.php:76     Symfony\Component\HttpKernel\HttpKernel->handleRaw()
  ./vendor/symfony/http-kernel/Kernel.php:197        Symfony\Component\HttpKernel\HttpKernel->handle()
  ./public/index.php:70                              Symfony\Component\HttpKernel\Kernel->handle()

Root cause:
GenericObject items are migrated to native GLPI Custom Assets (Glpi\CustomAsset\* namespace) which don't implement the uninstall() method.

Solution:
Add method_exists() check before calling uninstall() in hook.php to handle both legacy GenericObject classes and new Custom Assets.

[Rom1-B]

Please update CHANGELOG