SPRINGFIELD — Legal challenges to Illinois’ semiautomatic weapons ban began Wednesday with a federal complaint that the 8-day-old law prohibits “commonly possessed” and constitutionally protected guns. A state court pleading was also filed Wednesday, questioning the law’s exemptions based on a person’s employment.The state lawsuit seeks a temporary restraining order to stop enforcement of the law, which was inspired by the mass shooting that killed seven and injured 30 at the Highland …