JACKSONVILLE, Fla. — In a squalid dogfighting kennel, a champion named Bulletproof Sam sits in a makeshift wooden cage, his teeth exposed from a missing snout. Nearby, an undercover agent with the sheriff’s office meets with Sam’s breeder, a big-timer in the underground world of dogfighting named Willie Coleman, and makes a deal caught on a hidden video camera. Coleman — whose puppies other breeders nationwide sought for their prized bloodlines — was charged with 17 felony counts …