By Tzvi Machlin The Dallas Cowboys have no shortage of options at running back heading into the 2022 season. But they’re adding a veteran back to their ranks for some extra depth. According to NFL insider Ian Rapoport, the Cowboys are signing running back Ryan Nall to a deal. Nall plays primarily on special teams and has spent the last three seasons with the Chicago Bears. As a running back, Nall didn’t offer much to the Bears. The former undrafted free agent out of Oregon State had nine receptions for 71 yards and a touchdown plus 12 rushing yards in three seasons. Nall might wind up serving …