After agreeing to a partial deal to help fund a new Will County courthouse, officials in Joliet and the county know the city will kick in $10 million over a 10-year period for the project.On top of that, the city will waive $2.3 million in building fees and permits.But county officials don’t know exactly how long the project will take, what they will do with the old Jefferson Street courthouse or how they will pay for the rest of the estimated $150 million to replace their current 46-year-old complex.Construction is …