Add Herwig7 VH DSIDs to HWW samples receiving STXS decorations
Powheg+Herwig7 VH DSIDs are missing from the list of DSIDs which have STXS decorations applied to them (e.g., Powheg+Pythia8 VH). As they decorations are needed for estimation shower uncertainties for STXS templates, we add the Herwig7 DSIDs here.