MANCHESTER, N.H. — President Trump has decided to hire the longtime Washington lawyer Joseph E. diGenova, who has pushed the theory on television that Mr. Trump was framed by F.B.I. and Justice Department officials, to bolster his legal team, according to three people told of the decision. Mr. diGenova is not expected to take a lead role but will instead serve as a more aggressive player on the president’s legal team. Mr. Trump broke over the weekend from the longstanding advice of some of his lawyers that he refrain from directly attacking the special counsel, Robert S. Mueller III, a...