SCIP Dual Status

[ccoffrin]

I got a report that SCIP.jl does not support the solution dual_status parameter. I believe this parameter should be set to NO_SOLUTION if it is not available.

lanl-ansi/InfrastructureModels.jl#68

CC @mlubin, @odow, @rb004f

[odow]

I can fix this. It's just:

function MOI.get(::Optimizer, ::MOI.DualStatus)
    return MOI.NO_SOLUTION
end

[ccoffrin]

Thanks!