President Joe Biden's son Hunter Biden will appear on Oct. 3 in a federal court in Wilmington, Delaware, to face gun charges, a judge ordered on Wednesday, in the first-ever prosecution of a sitting U.S. president's child. Hunter Biden, 53, was indicted last week for allegedly lying on a form to acquire a handgun in 2018 and for being an illegal drug user in possession of the gun. His lawyer has said he plans to plead not guilty. Hunter Biden so…