Add a `rs_name` field to `IncompleteRecord`

So far we used `cc_name` in the generated bindings, assuming that it will be a valid identifier on the `.rs` side. This is however not true for forward declared class template specializations.

PiperOrigin-RevId: 456578468
diff --git a/rs_bindings_from_cc/ir.h b/rs_bindings_from_cc/ir.h
index a5ec007..777166a 100644
--- a/rs_bindings_from_cc/ir.h
+++ b/rs_bindings_from_cc/ir.h
@@ -613,6 +613,7 @@
 struct IncompleteRecord {
   llvm::json::Value ToJson() const;
   std::string cc_name;
+  std::string rs_name;
   ItemId id;
   BazelLabel owning_target;
   llvm::Optional<ItemId> enclosing_namespace_id;