ARLINGTON, Texas — Those tuning into Saturday night’s showdown at AT&T Stadium between the Detroit Lions and Dallas Cowboys were expecting a shootout. What they got was a rock fight, as both offenses were forced into dropping their weapons by a pair of defenses that preferred keeping the scoring to a minimum. And in the end, it was the Cowboys who pushed their home winning streak to 16 with a 20-19 win over Detroit that went to the wire in every sense, with the Lions having a winning 2-point conversion to Taylor Decker taken off the board with 23 seconds left because of illegal touching. Trail…