[Serialization] Reorganize module structure

plugins/kotlinx-serialization/testData/diagnostics/NoSuitableCtorInParent.kt

@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE
+// WITH_STDLIB
+// FILE: test.kt
+import kotlinx.serialization.*
+
+open class NonSerializableParent(val arg: Int)
+
+<!NON_SERIALIZABLE_PARENT_MUST_HAVE_NOARG_CTOR!>@Serializable<!>
+class Derived(val someData: String): NonSerializableParent(42)