This is in preparation to adding more types of 'SwRedlines'.

Change-Id: Id61217ed3c4622f7689427ea9f30e364f6bb65d1
Reviewed-on: https://gerrit.libreoffice.org/7410Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>