[API CHANGE] publish all of LibreOfficeKitClass, and the
getDocumentType callback for the LibreOfficeKitDocumentClass

Change-Id: I4d6529a71b29a0014053b797c67255df53a6ccde
Reviewed-on: https://gerrit.libreoffice.org/42243Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>