Add support for handling chunk generators in DFU

[alcatrazEscapee]

Tested using the reproduction case provided in the issue. Alternative version of #8940. This is meant to point out that it can be exactly this simple, if it is so desired. This does not require a mod to register anything with DFU to benefit from this fix.

Fixes https://github.com/MinecraftForge/MinecraftForge/issues/8915