[Serialization] Reorganize module structure

plugins/kotlinx-serialization/testData/boxWithoutRuntime/basic.kt

@@ -0,0 +1,23 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// TARGET_BACKEND: JVM_IR
+
+// WITH_STDLIB
+
+/**
+ * This test checks that in the case when serialization plugin is applied, but kotlinx-serialization-core runtime is not present in compile classpath,
+ * compilation of regular Kotlin classes still finishes succesfully.
+ *
+ * Such requirement is needed for cases when plugin is applied to a Gradle module, but runtime dependency is provided only in certain configurations,
+ * e.g. only in `testImplementation` configuration (see :wasm:wasm-ir module). In such setup, production sources have plugin applied, but no runtime in classpath.
+ */
+
+data class X(val i: Int) {
+    companion object {
+        fun x(): X = X(42)
+    }
+}
+
+fun box(): String {
+    val i = X.x().i
+    return if (i == 42) "OK" else i.toString()
+}