Fixed default twidth value for bblvlv and added new twidth_phsp parameter
This merge is to fix a couple small issues with bblvlv (AGENE-8376) in PowhegControl. By default we were using the NLO input value of the top width, while we should let bblvlv recalculate it at NLO, it now defaults to -1. And we lacked a twidth_phsp parameter, which was making the code crash at reweighting.