Fix to allow non violent golem farming

Golem/iron farms always involve some kind of killing mechanism for the golems. In 1.14 this will be much harder due to the new spawning mechanic. 

My idea: golems spawned by villagers automatically deconstruct when they are further than say 50 blocks from the center of the village, dropping 4 iron blocks. (equivalent to 36 iron ingots, this can be adjusted to make it less OP)

The advantage will be:

-no need to slowly kill villager golems in iron farms

-allows productive iron farms in 1.14 without drastically tweaking spawn rates, by providing a way to greatly increase the amount of iron harvested from each golem.

-It makes sense in terms of the iron golem being a 'magical/mechanical' entity that only holds together when within range of the source of its creating energy. (for player made golems, this would be the pumpkin.)