Get rid of slug_generator wiring
Get rid of slug_generator wiring

Instantiating a new SlugGenerator is simple enough to do inline in the
three places that care about it.

ministryofjustice/specialist-publisher,alphagov/specialist-publisher-rebuild,ministryofjustice/specialist-publisher,alphagov/specialist-publisher-rebuild,ministryofjustice/specialist-publisher,alphagov/specialist-publisher,alphagov/specialist-publisher-rebuild,alphagov/specialist-publisher,ministryofjustice/specialist-publisher,alphagov/specialist-publisher-rebuild,alphagov/manuals-publisher,alphagov/specialist-publisher,alphagov/manuals-publisher,alphagov/manuals-publisher