LibCpp: Support parsing enum classes

Author: https://github.com/itamar8910
Commit: c1ee0c1685
Pull-request: https://github.com/SerenityOS/serenity/pull/8260
Reviewed-by: https://github.com/alimpfard

Userland/Libraries/LibCpp/AST.h

@@ -505,6 +505,12 @@ public:
     {
     }
 
+    enum class Type {
+        RegularEnum,
+        EnumClass
+    };
+
+    Type type { Type::RegularEnum };
     Vector<StringView> m_entries;
 };