Changes for normal players

• Added cave biomes.
• River biomes no longer appear in oceans.
• Axolotls now spawn in underground pockets. Due to vanilla logic, they only spawn when clay is below them. Not all underground pockets will have clay in them.
• Molten rock in the core no longer spawns randomly. Instead, it's a smoother gradient.
• Fixed saplings failing to grow outside of big globe worlds.
• Fixed a lot of blocks not breaking quickly with the proper tool.
• Fixed a few blocks dropping the wrong items.
• Fixed bees not spawning in beehives in 1.20.5 and later.

Changes for data pack makers

• Layers (the chunk generator kind, not the rock layer kind) have been split up into separate files. They are no longer in the world preset.
  • This makes it easier to tweak them, but also means any data pack which already did this will need to update.
• Added a "noop"-typed layer, which does nothing, and does not have any configurable properties.
  • This layer type is intended for when you want to remove a layer with a data pack.
• The molten_rock configured feature type has been removed.
• Added new mechanism for data packs to add mob spawns to the world without replacing biomes.
• Added new weighted random switch statement for scripts.