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.*}

首先审查 pull request #1376，以及与 Hadoop 依赖、API 泄漏和 Java NIO 支持相关的 issue。该 issue 提议使用独立于 Hadoop 的 artifact，同时保留现有 artifact 中的兼容性，但没有定义已确定的设计或验收标准；开始之前请确认当前状态。

由索引模型根据 Issue 内容生成。