Chickens Lay Anything

This release adds support for Minecraft 1.21.2 (24w37a): The functionality has been reduced to just running a function as and at chickens when they lay an egg. This is because the minecraft:gameplay/chicken_lay loot table added in 24w37a makes this portion of the pack obsolete starting with that snapshot.

However, for versions 1.21 (and 1.21.1), an overlay has been provided, restoring the ability to customize the items "laid" by chickens.