BAJA CALIFORNIA, Mexico — They are called los desaparecidos — the disappeared. The term gained popularity among extralegal military and police forces in Argentina in the mid-1970s, describing people taken by government-backed armed forces. They vanished without a trace into a world void of human and legal rights. Today there is a different war being waged in Mexico, and a new class of los desaparecidos. More than 79,000 people have disappeared in the country, the vast majority since 2006 when former president Felipe Calderón launched Mexico’s war on drugs. Tijuana, a sprawling metropolis of 2….