snow golems spawn along side iron golems

WHAT:

for any village in a snowy biome, 0-4 snow golems should spawn with any iron golems that spawn.

WHY:

snow golem's snow balls would pair well with the iron golem's melee. snow balls do knock back but no damage. for example, if a skeleton were to spawn on a roof top, the iron golem would be helpless. that could change because snow golems could knock them off.

HOW:

snow golems would spawn at the same time an iron golem spawns in a cold village. the amount that spawns would depend on how populated the village is. the bigger the the village, the better the chance more snow golems will spawn.