USER-DPD Kokkos: propagate the new neigh_modify options from efaa4c67

Propogate the efaa4c67 changes to npair_ssa_kokkos from npair_kokkos that
support the new neigh_modify exclude molecule/intra and /inter options.
Note: npair_ssa_kokkos could inherit from npair_kokkos to avoid this kind
of missed change. Unfortunately, inheritance from templated classes is
both tricky and messy, and not worth the complexity in this case, IMHO.