Fir2Ir: more precise calculation of enum class modality

Use the same condition as in the already existing `createIrEnumEntry`
function (and as in psi2ir): enum class should be final unless there's
an enum entry with any declaration other than its constructor.

 #KT-57216

compiler/testData/ir/irText/expressions/temporaryInEnumEntryInitializer.fir.ir.txt

@@ -8,14 +8,14 @@ FILE fqName:<root> fileName:/temporaryInEnumEntryInitializer.kt
       BLOCK_BODY
         RETURN type=kotlin.Nothing from='public final fun <get-n> (): kotlin.Any? declared in <root>'
           GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:n type:kotlin.Any? visibility:private [final,static]' type=kotlin.Any? origin=null
-  CLASS ENUM_CLASS name:En modality:OPEN visibility:public superTypes:[kotlin.Enum<<root>.En>]
+  CLASS ENUM_CLASS name:En modality:FINAL visibility:public superTypes:[kotlin.Enum<<root>.En>]
     $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.En
     CONSTRUCTOR visibility:private <> (x:kotlin.String?) returnType:<root>.En [primary]
       VALUE_PARAMETER name:x index:0 type:kotlin.String?
       BLOCK_BODY
         ENUM_CONSTRUCTOR_CALL 'public constructor <init> (name: kotlin.String, ordinal: kotlin.Int) [primary] declared in kotlin.Enum'
           <E>: <root>.En
-        INSTANCE_INITIALIZER_CALL classDescriptor='CLASS ENUM_CLASS name:En modality:OPEN visibility:public superTypes:[kotlin.Enum<<root>.En>]'
+        INSTANCE_INITIALIZER_CALL classDescriptor='CLASS ENUM_CLASS name:En modality:FINAL visibility:public superTypes:[kotlin.Enum<<root>.En>]'
     PROPERTY name:x visibility:public modality:FINAL [val]
       FIELD PROPERTY_BACKING_FIELD name:x type:kotlin.String? visibility:private [final]
         EXPRESSION_BODY

compiler/testData/ir/irText/expressions/temporaryInEnumEntryInitializer.fir.kt.txt

@@ -2,7 +2,7 @@ val n: Any?
   field = null
   get
 
-open enum class En : Enum<En> {
+enum class En : Enum<En> {
   private constructor(x: String?) /* primary */ {
     super/*Enum*/<En>()
     /* <init>() */
@@ -29,3 +29,4 @@ open enum class En : Enum<En> {
     get(): EnumEntries<En> /* Synthetic body for ENUM_ENTRIES */
 
 }
+