Shaun White has a wedding to attend. So does fellow snowboarder Chloe Kim. Some, like freeskier Gus Kenworthy and Alpine racer Lindsey Vonn, said long ago they were staying away. Figure skater Mirai Nagasu is among four Olympians busy taping “Dancing with the Stars.” Most of the top skaters also have other commitments, so they can’t come either. Winter Olympians will descend on Washington for a week of festivities this week, capped with a visit to the White House on Friday.