Prince Harry and Joe Biden have been warned “the stakes are very high” as a court showdown looms. On Friday, the Duke of Sussex is set to have his day in court over whether he lied on his immigration papers so he could live in the US. The Heritage Foundation intends to force his papers to become public, to find out whether or not the duke lied about his previous drug use. The issue arose after Prince Harry, 39, admitted in his memoir Spare that he had taken drugs, leading to questions over why he was allowed to get a visa. Nile Gardiner, director of the Margaret Thatcher Center for Freedom at …