Make lava level configurable

Recently I made a datapack where I lowered the min Y to -256.

Shortly after doing this I realized under no circumstances could I lower the lava level.

Digging thru the code I found out its hardcoded at -54:

Aquifer.FluidStatus lavaStatus = new Aquifer.FluidStatus(-54, Blocks.LAVA.defaultBlockState());

It seems odd to allow us to drop the Y value via a datapack, but all caves below that will always be filled with lava due to the hardcoded level.

So it would be nice if this level could be configurable via a datapack, to allow us to truly lower the Y level of a world.