A tender and gently probing Norwegian drama about a pair of Oslo chimney sweeps whose lives are forever changed when they casually open up to each other in between jobs one morning, Dag Johan Haugerud’s “Sex” — the standalone first installment of the director’s Kieślowski-inspired “Sex, Love, Dreams” trilogy — is a far cry from the prurient spectacle promised by its title. Indeed, this sweet and chatty film, in which sex is often discussed but never depicted, could just as…