[FEA] JSON reader: ignores Java/C++ style comment

This is part of FEA of https://github.com/NVIDIA/spark-rapids/issues/9
We have a JSON file

``` json
{"name": // name
"Reynold Xin"}
```

Spark can parse it when enabling `allowComments` and `multiLine`

or

``` json
{'name': /* hello */ 'Reynold Xin'}
```

Spark can parse it when enabling `allowComments`

We expect there is a configure `allowComments` to control this behavior.