[BUGFIX] Deprecation free \Countable in AbstractCompositeValidator

Set #[\ReturnTypeWillChange] and corresponding @todo comments to
methods of implemented interfaces in AbstractCompositeValidator
to avoid deprecation messages without breaking compatibility.

Resolves: #95753
Releases: master
Change-Id: I0bbdabceefabc084d28ca8fc647339fb10d91a67
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71958


Tested-by: core-ci <typo3@b13.com>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/extbase/Classes/Validation/Validator/AbstractCompositeValidator.php

@@ -114,7 +114,9 @@ abstract class AbstractCompositeValidator implements ObjectValidatorInterface, \
      * Returns the number of validators contained in this conjunction.
      *
      * @return int The number of validators
+     * @todo Set to return type int as breaking change in v12.
      */
+    #[\ReturnTypeWillChange]
     public function count()
     {
         return count($this->validators);