Serializing timestamp from int (json raw decoder)

[spebern]

Which part is this question about

arrow-json

Describe your question

This test fails in arrow-json/src/raw/mod.rs, because 1681319393 is parsed via string conversion. Should it be possible to parse timestamps from ints? I think it was possible in the old json decoder.

    #[test]
    fn test_serialize_timestamp() {
        let json = vec![
            json!({"timestamp": 1681319393}),
            json!({"timestamp": "1970-01-01T00:00:00+02:00"}),
        ];
        let schema = Schema::new(vec![Field::new(
            "timestamp",
            DataType::Timestamp(TimeUnit::Second, None),
            true,
        )]);
        let mut decoder = RawReaderBuilder::new(Arc::new(schema))
            .build_decoder()
            .unwrap();
        decoder.serialize(&json).unwrap();
        let batch = decoder.flush().unwrap().unwrap();
        assert_eq!(batch.num_rows(), 1);
        assert_eq!(batch.num_columns(), 2);
        let values = batch.column(0).as_primitive::<Int64Type>().values();
        assert_eq!(values, &[1681319393, 1599572549]);
    }

Errror:

---- raw::tests::test_serialize_timestamp stdout ----
thread 'raw::tests::test_serialize_timestamp' panicked at 'called `Result::unwrap()` on an `Err` value: JsonError("failed to parse \"1681319393\" as Timestamp(Second, None): Parser error: Error parsing timestamp from '1681319393': error parsing date")', arrow-json/src/raw/mod.rs:1294:37
```

[tustvold]

label_issue.py automatically added labels {'arrow'} from #4073