Now, when Snapchat users search for “fenta,” “xanax” or other drug language, the results are blocked. They are redirected to an in-app video channel with content from nonprofit groups and the C.D.C. that addresses “fentapills” — the dangers of purported OxyContin, Percocet, Xanax and Adderall.According to Facebook’s latest community standards report, it took action on…