Add an option to the workflow which prevents hiding draft pages

Currently if a workflow is started for a draft document, the "hidden" flag for that document is set.

This makes it tricky for contributors to find that document via the normal navigation tree. I also cannot see the need for this, as the document is hidden by its view rights from all users except the ones in the corresponding workflow groups.

Thus I'd like to add an option to the workflow which allows to disable this feature, if wanted.