Treat SEALED_SUBCLASS_FQ_NAME_LIST change as a class signature change

#KT-19580

jps-plugin/testData/comparison/classSignatureChange/sealedClassNestedImplRemoved/old.kt

@@ -0,0 +1,12 @@
+package test
+
+sealed class Base1 {
+    class Nested1 : Base1()
+    class Nested2 : Base1()
+}
+
+sealed class Base2 {
+    class Nested1 : Base2()
+    class Nested2 : Base2()
+}
+