MultifileClassCodegen

- initial implementation
- new Kotlin file kinds + stub builder

libraries/stdlib/src/kotlin/jvm/JvmPlatformAnnotations.kt

@@ -50,6 +50,14 @@ public annotation class JvmStatic
 @MustBeDocumented
 public annotation class JvmName(public val name: String)
 
+/**
+ * Instructs the Kotlin compiler to generate a multifile class with this file as one o
+ */
+target(AnnotationTarget.FILE)
+@Retention(AnnotationRetention.RUNTIME)
+@MustBeDocumented
+public annotation class JvmMultifileClass
+
 /**
  * Instructs the Kotlin compiler to generate a public backing field for this property.
  */