Long before he was accused of killing second wife Bonny Lee Bakley, "Baretta" star Robert Blake set up a "contract" hit on his ex-wife and the actor she was dating, according to her shocking new testimony. Sondra Kerr-Blake said friends later told her of Blake's foiled plan to have her and Steve Railsback, best known for his role as Charles Manson in the TV flick "Helter Skelter," whacked in the late '70s, according to her deposition obtained by the Daily News. "I found out from several different people ... that he had put a 'contract' out on me and the...