[TASK] Allow strings in site configuration type "select"

To allow more usecases for extending the site configuration,
the value of tca type select should only be typecasted
if it looks like an integer.

Resolves: #87663
Releases: master, 9.5
Change-Id: I700bba3ac67ceac9acc8aa473d1b723b4bc34f4f
Reviewed-on: https://review.typo3.org/59666
Tested-by: TYPO3com <noreply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>

typo3/sysext/backend/Classes/Controller/SiteConfigurationController.php

@@ -42,6 +42,7 @@
 use TYPO3\CMS\Core\Messaging\FlashMessageService;
 use TYPO3\CMS\Core\Site\SiteFinder;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Core\Utility\MathUtility;
 use TYPO3\CMS\Fluid\View\StandaloneView;
 use TYPO3\CMS\Frontend\Page\PageRepository;
 use TYPO3Fluid\Fluid\View\ViewInterface;
@@ -300,7 +301,7 @@ protected function saveAction(ServerRequestInterface $request): ResponseInterfac
                         break;
 
                     case 'select':
-                        $newSysSiteData[$fieldName] = (int)$fieldValue;
+                        $newSysSiteData[$fieldName] = MathUtility::canBeInterpretedAsInteger($fieldValue) ? (int)$fieldValue : $fieldValue;
                         break;
 
                     default: