Washington (AFP) – Former president George W. Bush has stepped into the US debate on immigration, saying migrants are “a force for good” and arguing for a gradual process to allow undocumented immigrants to earn legal status. Bush, a past governor of Texas — a border state heavily impacted by migration — made his points in an op-ed article in the Washington Post previewing his new book “Out of Many, One: Portraits of America’s Immigrants.” The book, whose name comes from the nation’s Latin motto “E Pluribus unum,” features portraits of immigrants done by Bush himself, who self-deprecatingly …