It just exposes the two options available at libepubgen level already.

Change-Id: I428919ffe495b6d7ec2773f542e2fea6733d0a1c
Reviewed-on: https://gerrit.libreoffice.org/42241Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>