[FIR JS] Prepare the test data for FIR

compiler/testData/diagnostics/testsWithJsStdLib/native/delegation.fir.kt

@@ -0,0 +1,18 @@
+external interface I
+
+external object O : I
+
+
+class Delegate {
+    operator fun getValue(thisRef: Any?, property: Any): String = ""
+
+    operator fun setValue(thisRef: Any?, property: Any, value: String) {}
+}
+
+external class A : I by O {
+    val prop by Delegate()
+
+    var mutableProp by Delegate()
+}
+
+external val topLevelProp by Delegate()