Inner classes are no more allowed inside enum entries #KT-9750 Fixed

Forbidden use-case deleted from codegen tests

compiler/testData/diagnostics/tests/inner/illegalModifier.kt

@@ -15,8 +15,11 @@ class D {
 }
 
 enum class H {
+    I0 {
+        <!WRONG_MODIFIER_CONTAINING_DECLARATION!>inner<!> class II0
+    },
     <!WRONG_MODIFIER_TARGET!>inner<!> I {
-        inner class II
+        <!WRONG_MODIFIER_CONTAINING_DECLARATION!>inner<!> class II
     };
     
     inner class J

compiler/testData/diagnostics/tests/inner/illegalModifier.txt

@@ -82,6 +82,8 @@ public final class D {
 }
 
 public final enum class H : kotlin.Enum<H> {
+    enum entry I0
+
     enum entry I
 
     private constructor H()