Kapt: Do not use awkward ('$' -> '/') logic for KAPT3 class builder mode

So (for the most often reproduction case) #KT-19433 Fixed

Before this commit, internal names for nested classes were written as test/Foo/Bar (comparing to test/Foo$Bar in the normal mode), as getting qualified names from such internal names was trivial. But, because of IC, we needed to write class files to the disk, so our decompiler could find such "broken" classes and read it in a wrong way.

compiler/backend/src/org/jetbrains/kotlin/codegen/state/KotlinTypeMapper.java

@@ -99,20 +99,6 @@ public class KotlinTypeMapper {
     private final boolean isJvm8TargetWithDefaults;
 
     private final TypeMappingConfiguration<Type> typeMappingConfiguration = new TypeMappingConfiguration<Type>() {
-        private final Function2<String, String, String> defaultClassNameFactory
-                = TypeMappingConfiguration.Companion.getDEFAULT_INNER_CLASS_NAME_FACTORY();
-
-        private final Function2<String, String, String> innerClassNameFactory = new Function2<String, String, String>() {
-            @Override
-            public String invoke(String outer, String inner) {
-                if (classBuilderMode == ClassBuilderMode.KAPT3) {
-                    return outer + '/' + inner;
-                }
-
-                return defaultClassNameFactory.invoke(outer, inner);
-            }
-        };
-
         @NotNull
         @Override
         public KotlinType commonSupertype(@NotNull Collection<KotlinType> types) {
@@ -122,7 +108,7 @@ public class KotlinTypeMapper {
         @NotNull
         @Override
         public Function2<String, String, String> getInnerClassNameFactory() {
-            return innerClassNameFactory;
+            return TypeMappingConfiguration.DefaultImpls.getInnerClassNameFactory(this);
         }
 
         @Nullable