Row converter does not preserve list lengths of List(Null)

[kawadakk]

Describe the bug
RowConverter::convert_rows always decodes List(Null) as empty lists.

To Reproduce

let mut builder = GenericListBuilder::<O, _>::new(NullBuilder::new());
builder.values().append_nulls(0);
builder.append(true);
builder.append(false);
builder.values().append_nulls(2);
builder.append(true);

let list = Arc::new(builder.finish()) as ArrayRef;
let d = list.data_type().clone();

let converter = RowConverter::new(vec![SortField::new(d.clone())]).unwrap();

let rows = converter.convert_columns(&[Arc::clone(&list)]).unwrap();
assert!(rows.row(0) > rows.row(1)); // [null] > null
assert!(rows.row(0) < rows.row(2)); // [null] < [null, null]
assert!(rows.row(1) < rows.row(2)); // null < [null, null]

let back = converter.convert_rows(&rows).unwrap();
assert_eq!(back.len(), 1);
back[0].to_data().validate_full().unwrap();
assert_eq!(&back[0], &list);

Adding the above code to test_single_list in arrow-row/src/lib.rs causes a test failure:

thread 'tests::test_list' panicked at arrow-row/src/lib.rs:2111:9:
assertion `left == right` failed
  left: ListArray
[
  NullArray(0),
  null,
  NullArray(0),
]
 right: ListArray
[
  NullArray(0),
  null,
  NullArray(2),
]

Expected behavior
Not panicking

Additional context