Improved Snowfall

In light of the new snowAccumulationHeight game rule in snapshot 22w44a, I would like to propose some new mechanics for how exactly snow piles up on top of other snow. 

If snow tries to generate on a block where one of the neighbouring blocks has less snow layers, the snow will fall on that block instead. This makes snow generation less patchy and random-looking. It'll look more smooth, even, and uniform, like real snow.