[BUGFIX] Fix namespace of validation error in form

The FormElementHooks now uses the correct namespace
for the generated error.

The TranslateElementErrorViewHelper requires the submitted
error to be an instance of TYPO3\CMS\Extbase\Validation\Error.
The error was an instance of TYPO3\CMS\Extbase\Error\Error.
As the instance was wrong, an exception was thrown.

Resolves: #85255
Releases: master, 8.7
Change-Id: I6ccce5fb6370d2bf34f494141d73cc602eb923ce
Reviewed-on: https://review.typo3.org/57211
Reviewed-by: Ralf Zimmermann <ralf.zimmermann@tritum.de>
Tested-by: Ralf Zimmermann <ralf.zimmermann@tritum.de>

typo3/sysext/form/Classes/Hooks/FormElementHooks.php

@@ -15,8 +15,8 @@
  */
 
 use TYPO3\CMS\Core\Utility\GeneralUtility;
-use TYPO3\CMS\Extbase\Error\Error;
 use TYPO3\CMS\Extbase\Object\ObjectManager;
+use TYPO3\CMS\Extbase\Validation\Error;
 use TYPO3\CMS\Form\Domain\Model\Renderable\RenderableInterface;
 use TYPO3\CMS\Form\Domain\Model\Renderable\RootRenderableInterface;
 use TYPO3\CMS\Form\Domain\Runtime\FormRuntime;