[BUGFIX] FormEngine: Support description in BackendLayoutWizardElement

Have TCA 'description' field for renderType=belayoutwizard.
See styleguide elements basic -> text -> text_20 before/after.

Resolves: #94079
Releases: master, 10.4
Change-Id: I18d8001904e97384b15d825253919465f90c4a06
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69057


Tested-by: core-ci <typo3@b13.com>
Tested-by: Jochen <rothjochen@gmail.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Jochen <rothjochen@gmail.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>