In Arizona, 1981 started with a bang. A few minutes after the year had begun, Gilbert Dixon, 35, was walking in an alley next to a UTotem convenience store at 602 N. First Ave. Into the alley came a car, with one of its two occupants firing a pistol into the air. "Happy New Year," Dixon cried, and the man with the gun shot him in the leg. In a way, 1981 was a year that both justified Dixon's optimism and reflected his fate. On the bright side, a warrior came home from captivity to a hero's welcome, an Arizonan made history by becoming the first woman member of the U.S. Supreme Court, and a Mesa woman survived a drastic heart-lung transplant. On the dark side, two men were convicted of a brutal contract killing that occurred on the eve of the new year, a Tucson bank was the target of the largest bank robbery in the nation's history, and a valley in southern Arizona crackled with tension as longtime residents clashed with gun-toting members of a religious cult. It also was a year for offbeat items - topped by the story of true belitJvtrs who planned to end the year in heaven but who had to Republic. settle for Arizona. An oddball entry was one of the first in line for the year. In January, Granvel Downing, a 40- year-old Phoenix construction worker, said he had received a $500 settlement in a lawsuit that he filed after finding a lizard in a bottle of Coke on Sept. 7, 1978. The defendants were the Phoenix Coca-Cola Bottling Co. and Circle K Corp. Downing's lawyer said one of the