Make ParquetReader(List<InputFile>, ParquetReadOptions, ReadSupport<T>) constructor public

My application uses s3 storage to store parquet files. The problem is that there is not ability to get rid from `new Configuration(true);` which load configuration from files:
`core-default.xml` and `core-site.xml` every time when ParquetReader instance is created.

I suggest just make ParquetReader(List<InputFile>, ParquetReadOptions, ReadSupport<T>) constructor public then there will be ability to do custom builder.