[Feature] Dim 0 control

[ocots]

We can introduce the possibility to solve problems without control to optimise, simply variables.

@jbcaillau @PierreMartinon @joseph-gergaud @abavoil please add here case studies.

Issues to complete:

• [Feature] Dim 0 control CTModels.jl#282
• [Feature] Dim 0 control CTParser.jl#240
• [Feature] Dim 0 control CTDirect.jl#575