[Python] CSV and JSON options lack a nice repr/str

### Describe the enhancement requested

This could be improved:
```console
>>> from pyarrow import csv, json
>>> csv.ReadOptions(use_threads=False)
<pyarrow._csv.ReadOptions at 0x7d0a711b5300>
>>> json.ReadOptions(use_threads=False)
<pyarrow._json.ReadOptions at 0x7d0a22e113b0>
```

(same for the other option classes in these modules)

### Component(s)

Python