What appears to be a nightly newscast is about to begin, only with a very Ukrainian twist: Everything is a lie, from start to finish. “Welcome to ‘StopFake,’ the place where we set the record straight on fakes about Ukraine,” the anchor, Margo Gontar, intones. In other parts of the world, viewers might suspect the evening news is just a bunch of lies, but watching the weekly broadcast of “StopFake News,” they can be certain of it.