Implement light classes for Kotlin scripts

compiler/testData/asJava/lightClasses/script/InnerClasses.kts

@@ -0,0 +1,13 @@
+// InnerClasses
+
+class Bar(val a: Int) {
+    val b: Int = 0
+
+    fun getAPlusB() = a + b
+
+    class Baz {
+        fun doSomething() {
+
+        }
+    }
+}