Kotlin module name not used

[LuminaSapphira]

The module_name member of the Kotlin language struct does not seem to have any usages. If it is unused we should either give it a use or remove it. It appears based on CLI help output that it was controlled something about serialization, but we seem to be only supporting kotlinx.serialization so is it still necessary?

Relevant member: https://github.com/1Password/typeshare/blob/f99eb479f2649c02ca7d37240b829ec6b36e917c/core/src/language/kotlin.rs#L19

Relevant help output:

    -m, --module-name <MODULENAME>
            Kotlin serializer module name