GRAND RAPIDS, Mich. — The retrial of two men accused of a violent plot to kidnap Gov. Gretchen Whitmer opened in federal court on Wednesday, with attorneys for both sides recasting and reframing their arguments four months after the first trial ended in a hung jury. Federal prosecutors made a dramatic pivot, talking more directly from the outset of the trial about the involvement of informants and undercover agents in an effort to depict defendants Adam Fox, 39, and Barry Croft Jr., 46, as individuals with a concrete desire to overthrow the government and spark a second American Revolution — l…