NEW ORLEANS — A lawsuit is challenging a Louisiana court system’s use of fees people pay upon conviction of misdemeanor crimes to pay a judge’s salary and other court expenses.On Tuesday, the New Orleans-based Roderick and Solange MacArthur Justice Center filed a class-action lawsuit to overturn the “conviction fee” system in Ascension Parish.The suit was filed in federal court in Baton Rouge, La., on behalf of Richard Williams, who lives in Gonzales. The center said Williams was cited on Nov. …