This week, American Ballet Theater plans to rock out. For the company's City Center season, the artistic director Kevin McKenzie commissioned David Parsons, Ann Reinking, Natalie Weir and Stanton Welch to find inspiration in the music of George Harrison. No concert T-shirts, no lighters, no marijuana. Just the trailing scent of Chanel and ballet patrons, clad in black tie, playing air guitar in the aisles. The mind reels.