rest(visitor): avoid fully deserializing dynamic field (#19521)

## Description

Make it so that deserializing dynamic field info does not inflate the
whole field -- just the outer struct -- which in turn means that this
operation cannot fail.

## Test plan

```
sui$ cargo simtest
sui-adapter-transactional-tests$ cargo simtest
```

## Stack

- #19517 
- #19518 
- #19519 
- #19520 

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:
- [ ] REST API:

crates/sui-core/src/rest_index.rs

@@ -20,7 +20,7 @@ use sui_types::base_types::ObjectID;
 use sui_types::base_types::SequenceNumber;
 use sui_types::base_types::SuiAddress;
 use sui_types::digests::TransactionDigest;
-use sui_types::dynamic_field::{DynamicFieldInfo, DynamicFieldType};
+use sui_types::dynamic_field::visitor as DFV;
 use sui_types::full_checkpoint_content::CheckpointData;
 use sui_types::layout_resolver::LayoutResolver;
 use sui_types::messages_checkpoint::CheckpointContents;
@@ -671,45 +671,26 @@ fn try_create_dynamic_field_info(
         return Ok(None);
     }
 
-    let (name_value, dynamic_field_type, object_id) = {
-        let layout = sui_types::layout_resolver::into_struct_layout(
-            resolver
-                .get_annotated_layout(&move_object.type_().clone().into())
-                .map_err(StorageError::custom)?,
-        )
-        .map_err(StorageError::custom)?;
-
-        let move_struct = move_object
-            .to_move_struct(&layout)
-            .map_err(StorageError::serialization)?;
-
-        // SAFETY: move struct has already been validated to be of type DynamicField
-        DynamicFieldInfo::parse_move_object(&move_struct).unwrap()
-    };
-
-    let name_type = move_object
-        .type_()
-        .try_extract_field_name(&dynamic_field_type)
-        .expect("object is of type Field");
-
-    let name_value = name_value
-        .undecorate()
-        .simple_serialize()
-        .expect("serialization cannot fail");
-
-    let dynamic_object_id = match dynamic_field_type {
-        DynamicFieldType::DynamicObject => Some(object_id),
-        DynamicFieldType::DynamicField => None,
-    };
+    let layout = resolver
+        .get_annotated_layout(&move_object.type_().clone().into())
+        .map_err(StorageError::custom)?
+        .into_layout();
 
-    let field_info = DynamicFieldIndexInfo {
-        name_type,
-        name_value,
-        dynamic_field_type,
-        dynamic_object_id,
-    };
+    let field = DFV::FieldVisitor::deserialize(move_object.contents(), &layout)
+        .map_err(StorageError::custom)?;
 
-    Ok(Some(field_info))
+    let value_metadata = field.value_metadata().map_err(StorageError::custom)?;
+
+    Ok(Some(DynamicFieldIndexInfo {
+        name_type: field.name_layout.into(),
+        name_value: field.name_bytes.to_owned(),
+        dynamic_field_type: field.kind,
+        dynamic_object_id: if let DFV::ValueMetadata::DynamicObjectField(id) = value_metadata {
+            Some(id)
+        } else {
+            None
+        },
+    }))
 }
 
 fn try_create_coin_index_info(object: &Object) -> Option<(CoinIndexKey, CoinIndexInfo)> {