CHICAGO — A federal judge in Chicago struck down a key immigration rule Monday that would deny green cards to immigrants who use food stamps or other public benefits, a blow to the Trump administration on the eve of the election.In a decision that applies nationwide, U.S. District Judge Gary Feinerman rejected the rule that had taken effect recently after the U.S. Supreme Court reversed a hold on the policy following lawsuits. Among other things, Feinerman said the rule violates the Administrative Procedure Act, which …