by Quendrith Johnson, Los Angeles Correspondent While Kim Ki-duk has been building an international presence for years with films that are often crushing in their ability to communicate the human condition, PIETA, his 18th film may very well mark his breakout in the American market.    For PIETA, which screened at AFI's Film Fest on Nov. 2, Kim surfs the zeitgeist of global unrest in a tumultuous economic climate with an exploration of an unusual 'mother-son' dyn...