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ARROW-4674: [JS] Update arrow2csv to new Row API

This PR updates `arrow2csv` cell measurement to iterate the Row values, now that `length` is a Symbol. Closes https://issues.apache.org/jira/browse/ARROW-4674.

Before:
```
       "row_id" | "0: Float64" | "1: Utf8"
              0 | 3.141592653589793 |     "foo"
              1 | 1.5707963267948966 |     "bar"
              2 | 1.0471975511965976 |     "baz"
              3 |          0.7 |    "bork"
```

After:
```
       "row_id" |       "0: Float64" | "1: Utf8"
              0 |  3.141592653589793 |     "foo"
              1 | 1.5707963267948966 |     "bar"
              2 | 1.0471975511965976 |     "baz"
              3 |                0.7 |    "bork"
```

Author: ptaylor <paul.e.taylor@me.com>

Closes #3747 from trxcllnt/js/arrow2csv-cell-measurement and squashes the following commits:

31e572c1 <ptaylor> cleanup
71f1a59c <ptaylor> make arrow2csv iterate the Row values
36826895 <ptaylor> remove length from RowLike type
62dff4a6 <ptaylor> ensure numbers/bigint don't use JSON.stringify()