Ever since Congress started murmuring about abolishing the supposedly left-leaning and elitist institutions of American public broadcasting over a decade ago, NPR and PBS seem to have been running either to the right or just to blandness. So the fact that an action-packed new cop drama is being produced by public television might qualify as a minor surprise. Even more surprising is that the producers of “Cop Shop” are taking some serious shots at the FCC’s recent crackdown on “indecency.”