[K/JS] Deprecate external enum declarations

^KT-57254 Fixed

compiler/testData/diagnostics/testsWithJsStdLib/native/inlineClass.kt

@@ -1,10 +1,11 @@
 // FIR_IDENTICAL
 // !LANGUAGE: +InlineClasses, -JvmInlineValueClasses
+// !DIAGNOSTICS: +ENUM_CLASS_IN_EXTERNAL_DECLARATION_WARNING
 
 external inline class <!WRONG_EXTERNAL_DECLARATION!>C(<!EXTERNAL_CLASS_CONSTRUCTOR_PROPERTY_PARAMETER!>val a: Int<!>)<!> {
     fun foo()
 }
 
-<!WRONG_MODIFIER_TARGET!>inline<!> external enum class <!WRONG_EXTERNAL_DECLARATION!>E<!> {
+<!WRONG_MODIFIER_TARGET!>inline<!> external enum class <!ENUM_CLASS_IN_EXTERNAL_DECLARATION_WARNING, WRONG_EXTERNAL_DECLARATION!>E<!> {
     A
 }