simplify inplace ListOps

With all list types being movable, can now collapse out the code duplication of things like inplaceReorder. Eg,

template<unsigned Width>
void Foam::inplaceReorder
(
    const labelUList& oldToNew,
    PackedList<Width>& input,
    const bool prune
)
{
    input = reorder(oldToNew, input, prune);
}

since the rvalue returned from reorder() now hooks into the move assignment operator