Dual variable of the path constraints

[ocots]

When building the solution, we must pass the dual variable of the path constraints:

CTDirect.jl/src/solution.jl

Line 46 in 9c39f60

path_constraints_dual=path_constraints_dual,

Actually, the dual variable should be divided by the step length:

https://github.com/control-toolbox/OptimalControl.jl/blob/ea1e64bc9b55dbcd68bf43ac176679c30f3b9421/test/extras/cons.jl#L49