A Facile Synthesis of 5‐Amino‐1‐aryl‐4‐cyanoimidazoles and 5‐Amino‐1‐ aryl‐4‐(cyanoformimidoyl)‐1H‐imidazoles from N‐Aryl‐N′‐(1,2‐ dicyanovinyl)formamidines