jextract/jni: Propagate generic parameters to Case types of generic enums

[sidepelican]

This PR is the first step toward supporting the extraction of generic associated values from generic enum.

Currently, the generated Case types for generic enums do not carry generic parameters.
While this isn't causing immediate issues, these parameters will be necessary in the future when we want to extract generic associated values from the Case.

public sealed interface Case {
  // `Wrapped` is not usable from the static context
  record Some(Wrapped arg0) implements Case {}
  record None() implements Case {}
}

This PR focuses solely on propagating the generic parameters of the enum type down to its Case type.

During this work, I encountered and fixed an issue in wrap-java where translation was failing when a nested type's parent type was generic.

---

Note

I have loved contributing to swift-java for a half year, but unfortunately, I have run out of time to continue doing so.
While I will keep following the development of swift-java, I won't be able to actively contribute as I did before.

Thank you so much for all your valuable code reviews.

[ktoso]

Oh too bad to hear you won’t have more time contributing … maybe in some hobby time :-)

Thanks for all the contributions, it’s all accounted for very useful improvements!