Fix a bug and add experimental support for minecraft 1.17
This version adds support for minecraft 1.17, but it will require a KnokkoCore for minecraft 1.17 and is still experimental (due to very limited testing). Note: this plug-in might be broken on earlier minecraft versions as well due to some refactorings for 1.17.
It also fixes a bug that would make it harder to change the drops of a custom block in some circumstances.