Deprecation: #85802 - Move FlexFormService from EXT:extbase to EXT:core

See Issue #85802

Description

Move FlexFormService from EXT:extbase to EXT:core.

Impact

The PHP class TYPO3\CMS\Extbase\Service\FlexFormService has been moved from the system extension extbase to core. The PHP class has been renamed to TYPO3\CMS\Core\Service\FlexFormService.

Affected Installations

Any TYPO3 installation where this PHP class is in use within a TYPO3 extension.

Migration

Use the new namespace to reference the TYPO3\CMS\Core\Service\FlexFormService.