Treat SEALED_SUBCLASS_FQ_NAME_LIST change as a class signature change

#KT-19580

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

@@ -0,0 +1,9 @@
+package test
+
+sealed class Base1
+class Impl1 : Base1()
+class Impl11 : Base1()
+
+sealed class Base2
+class Impl2 : Base2()
+class Impl22 : Base2()