“Barbenheimer” may be the gift that keeps on giving. After Greta Gerwig’s “Barbie” and Christopher Nolan’s “Oppenheimer” ignited the summer box office, the blockbusters with twin release dates are bringing populist energy to the Oscars. Yet the one-two punch of “Barbie” ($1.445 billion globally) and “Oppenheimer” ($957 million), along with a valiant assist from Martin […]