[BUGFIX] EXT:form - handle boolean finisher options

Properly store boolean form definition values. Also
boolean finisher options are returned as boolean now.

Resolves: #82569
Releases: master, 8.7
Change-Id: I1eee0c6d8eaf07534d31622025f3c954d608627b
Reviewed-on: https://review.typo3.org/54226


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Daniel Lorenz <daniel.lorenz@extco.de>
Tested-by: Daniel Lorenz <daniel.lorenz@extco.de>
Reviewed-by: Carlos Meyer <cm@davitec.de>
Tested-by: Carlos Meyer <cm@davitec.de>
Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Tested-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>