[C++] sum doesn't check for overflow

### Describe the bug, including details regarding any error messages, version, and platform.

```pycon
>>> pc.sum(pa.array([2**63, 2**63], type=pa.uint64()))
<pyarrow.UInt64Scalar: 0>
>>> pc.sum(pa.array([2**62, 2**62], type=pa.int64()))
<pyarrow.Int64Scalar: -9223372036854775808>
```


### Component(s)

C++