K2 Scripting: restore some codegen scripting tests for K2

compiler/testData/codegen/box/script/scriptNestedClassInstanceK2.kt

@@ -0,0 +1,14 @@
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND_K1: JVM, JVM_IR, JS_IR, JS_IR_ES6
+// IGNORE_LIGHT_ANALYSIS
+// WITH_STDLIB
+// FILE: test.kt
+
+fun box(): String =
+    Nested().x
+
+// FILE: script.kts
+
+class Nested {
+    val x = "OK"
+}