Prosecutors rested their case Tuesday at R. Kelly’s federal trial in Chicago after presenting two weeks of evidence and testimony from four Kelly accusers in their bid to prove the singer enticed underage girls for sex, produced child pornography and successfully rigged his 2008 state trial.Among the last prosecution witnesses was a 42-year-old woman who went by the pseudonym “Nia.” Taking the stand Tuesday morning, she was the fourth and final accuser to testify against Kelly at the trial in his hometown. A fifth accuser …