[!!!][TASK] Deprecate FormEngine::sL()

This patch deprecates FormEngine::sL() and removes
the dependency from all form element classes.

Resolves: #63855
Releases: master
Change-Id: I58a596c9c8c09f18f5129cd64dd1e76296d37f3f
Reviewed-on: http://review.typo3.org/35466
Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>