make it easy to read and write parquet files in java without depending on hadoop

I am happy to help with this but I'd love some guidance on:

1) likelihood of being accepted as a patch.
2) how critical it is to maintain backwards compatibility in APIs.

For instance, we probably want to introduce a new artifact that lives under the existing hadoop depending artifact, and move as much code as possible to that, keeping the hadoop apis in the old artifact.

Welcome comments on solving this issue.

**Reporter**: [Oscar Boykin](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=posco)
#### Related issues:
- [Make ParquetIO Read splittable](https://issues.apache.org/jira/browse/BEAM-4379) (blocks)
- [hadoop-common is not an optional dependency](https://github.com/apache/parquet-java/issues/2556) (is duplicated by)
- [Avoid leaking Hadoop API to downstream libraries](https://github.com/apache/parquet-java/issues/2097) (incorporates)
- [Add Java NIO Avro OutputFile InputFile](https://github.com/apache/parquet-java/issues/2447) (is related to)
#### PRs and other links:
- [GitHub Pull Request #1376](https://github.com/apache/parquet-java/pull/1376)

_{**Note**: *This issue was originally created as [PARQUET-1126](https://issues.apache.org/jira/browse/PARQUET-1126). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Inizia esaminando la pull request #1376 e le issue correlate relative alle dipendenze Hadoop, alle perdite dell’API e al supporto di Java NIO. La issue propone un artifact indipendente da Hadoop, preservando al contempo la compatibilità nell’artifact esistente, ma non definisce un design stabilito né criteri di accettazione; conferma lo stato attuale prima di iniziare.

Scritto dal modello di indicizzazione a partire dal testo della issue.