[TASK] EXT:form - add empty option to select elements

Add configuration for fluid's select VH attribute 'prependOptionLabel'.

Resolves: #80192
Releases: master
Change-Id: Id045fac0d4d65ab4127607ec4ed1384757a0201f
Reviewed-on: https://review.typo3.org/52018


Reviewed-by: Bjoern Jacob <bjoern.jacob@tritum.de>
Tested-by: Bjoern Jacob <bjoern.jacob@tritum.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Tested-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>