IR: add IrClass.hasEnumEntries

This flag will be used on JVM to determine whether or not to generate
external enum entries mappings ("$EntriesMappings") classes. Note that
from the frontend's point of view, every enum has `entries`, so for
backend purposes we have to reach out to the underlying deserialized
data to read the flag from the metadata.

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeclarationDeserializer.kt

@@ -374,6 +374,7 @@ class IrDeclarationDeserializer(
                     isValue = flags.isValue,
                     isExpect = flags.isExpect,
                     isFun = flags.isFun,
+                    hasEnumEntries = flags.hasEnumEntries,
                 )
             }.usingParent {
                 typeParameters = deserializeTypeParameters(proto.typeParameterList, true)

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/encodings/BinaryFlags.kt

@@ -33,6 +33,7 @@ value class ClassFlags(val flags: Long) {
     val isExpect: Boolean get() = IrFlags.IS_EXPECT_CLASS.get(flags.toInt())
     val isExternal: Boolean get() = IrFlags.IS_EXTERNAL_CLASS.get(flags.toInt())
     val isFun: Boolean get() = IrFlags.IS_FUN_INTERFACE.get(flags.toInt())
+    val hasEnumEntries: Boolean get() = IrFlags.HAS_ENUM_ENTRIES.get(flags.toInt())
 
     companion object {
         fun encode(clazz: IrClass, languageVersionSettings: LanguageVersionSettings): Long {