Load Java enums as final classes

In case Java enum has an abstract member, it has the ACC_ABSTRACT flag
set in the bytecode. However, we should still load it with final
modality to be consistent with Kotlin enums which are always considered
final

 #KT-23426 Fixed

compiler/testData/loadJava/compiledJava/enum/EnumWithSpecializedEntry.txt

@@ -1,6 +1,6 @@
 package test
 
-public open enum class EnumWithSpecializedEntry : kotlin.Enum<test.EnumWithSpecializedEntry!> {
+public final enum class EnumWithSpecializedEntry : kotlin.Enum<test.EnumWithSpecializedEntry!> {
     enum entry E1
 
     enum entry E2