Add Java serializable support for JVM

[MV-GH]

With K2 this is possible again.

Common

expect interface JavaSerializable

data class Post(val name: String) : JavaSerializable

JVM

actual interface JavaSerializable: java.io.Serializable

fun main() {
    val post = Post("Hello")
    println(post)
    println(post is java.io.Serializable) // True
}