Add test for check access flags in class file (refactor WriteAccessFlagTest)

compiler/testData/writeFlags/class/accessFlags/publicFinalInnerClass.kt

@@ -0,0 +1,8 @@
+public class Foo() {
+   public class MyClass() {
+   }
+}
+
+// TESTED_OBJECT_KIND: class
+// TESTED_OBJECTS: Foo$MyClass
+// FLAGS: ACC_FINAL, ACC_PUBLIC, ACC_SUPER