In another move to make sure it has what it needs to electrify its lineup, General Motors Co. said Thursday it entered into a supply agreement with MP Materials Corp. for the alloy and magnets needed for EV programs. The agreement solidifies terms of a binding agreement announced by the companies in December. MP Materials will supply U.S.-sourced and manufactured rare earth materials — alloy and finished magnets — for electric motors in more than a dozen models using GM’s new Ultium EV platform. MP is planning a gradual production ramp-up starting in late 2023 with alloy. The supply agreement …