[General] Return dual variable

[ocots]

I need to return the dual variable if any here:

CTFlows.jl/ext/types.jl

Lines 147 to 160 in ebb8b12

	sol = CTModels.build_solution(
	ocp,
	Vector{Float64}(T), #::Vector{Float64},
	X,
	U,
	v, #::Vector{Float64},
	P;
	iterations=-1,
	constraints_violation=-1.0,
	message="no message",
	stopping=:nostoppingmessage,
	success=true,
	kwargs_OCS...
	)