Write parquet to STDOUT

https://github.com/Parquet/parquet-mr/blob/master/parquet-hadoop/src/main/java/parquet/hadoop/ParquetWriter.java

I would like to write the parquet to stdout but there is no option to let me do this. Also the file must not already exist, or I' ll get Exception.

Thanks

**Reporter**: [Federico Ponzi](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=federicoponzi)

_{**Note**: *This issue was originally created as [PARQUET-570](https://issues.apache.org/jira/browse/PARQUET-570). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

从 parquet-hadoop/src/main/java/parquet/hadoop/ParquetWriter.java 开始，跟踪输出路径的打开方式以及现有文件检查的应用方式。确定可以在哪里支持 stdout 目标，同时不破坏正常的文件输出。完成的标准是：可以通过一个有文档说明的选项将 parquet 数据写入 stdout，并且有针对新行为的覆盖测试。

由索引模型根据 Issue 内容生成。