[Serialization] Reorganize module structure

plugins/kotlinx-serialization/testData/firMembers/inlineClasses.kt

@@ -0,0 +1,19 @@
+// WITH_STDLIB
+
+import kotlinx.serialization.*
+import kotlinx.serialization.json.*
+import kotlinx.serialization.internal.*
+
+@Serializable
+@JvmInline
+value class Foo(val i: Int)
+
+@Serializable
+class Holder(val f: Foo)
+
+fun box(): String {
+    if(!Foo.serializer().descriptor.isInline) return "Incorrect descriptor"
+    val s = Json.encodeToString(Holder.serializer(), Holder(Foo(42)))
+    if (s != """{"f":42}""") return s
+    return "OK"
+}