ALLEN PARK, Mich. — While the national spotlight has been understandably centered on the quarterback matchup heading into this weekend’s playoff tilt between the Detroit Lions and Los Angeles Rams, there’s another significant organizational overlap worthy of attention. The game will pit franchise roster-builders — mentor and mentee — Rams GM Les Snead and Lions counterpart Brad Holmes. Holmes was already several years into his time with the Rams when Snead arrived in 2012 to serve as the team’s general manager. The two had known each other previously, having frequently crossed paths in Atlanta…