In a conflict where choosing one side feels like the only option, Palestinian-Israeli actor Yousef Sweid dives into the chaos of identity, truth and family life in “Between the River and the Sea.” Raised as a Christian-Arab kid in Haifa, now raising two Jewish-Arab kids in Berlin, he unpacks his “in-between-ness” in a new Berlin show that’s playing to sold-out crowds. Rebecca Rosman has the story.