John Durham’s team has sought information about the F.B.I.’s handling of the Clinton Foundation investigation, raising questions about the scope of the prosecutor’s review. WASHINGTON — From the beginning, John H. Durham’s inquiry into the Russia investigation has been politically charged. President Trump promoted it as certain to uncover a “deep state” plot against him, Attorney General William P. Barr rebuked the investigators under scrutiny, and he and Mr. Durham publicly second-guessed an independent inspector general and traveled the globe to chase down conspiracy theories.