[K/JS] Deprecate external enum declarations

^KT-57254 Fixed

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

@@ -1,4 +1,5 @@
 // FIR_IDENTICAL
+// !DIAGNOSTICS: +ENUM_CLASS_IN_EXTERNAL_DECLARATION_WARNING
 external interface I {
     interface J
 
@@ -6,7 +7,7 @@ external interface I {
 
     <!NESTED_CLASS_IN_EXTERNAL_INTERFACE!>object O<!>
 
-    enum class <!NESTED_CLASS_IN_EXTERNAL_INTERFACE!>E<!>
+    enum class <!ENUM_CLASS_IN_EXTERNAL_DECLARATION_WARNING, NESTED_CLASS_IN_EXTERNAL_INTERFACE!>E<!>
 
     companion <!NESTED_CLASS_IN_EXTERNAL_INTERFACE!>object<!>
 }