John Hopewell Chief International CorrespondentProducer of Argentina’s Oscar entry “Sleepwalkers,” Juan Pablo Miller’s Buenos Aires-based Tarea Fina has unveiled “El Hijo Deseado,” the next film by Berlinale Jury Grand Prix winner Ariel Rotter (“The Other,” “Incident Light”).Its announcement comes as Tarea Fina advances on post-production of “La Encomienda,” from Pablo Giorgelli, whose “Las Acacias” was awarded the Cannes Festival’s Camera d’Or for best first feature by a jury presided by