Enhance ParquetWriter with exposing in-memory size of writer object

While using ParquetWriter and before closing it to write the content out to the disk, there is no way to check/estimate the size of the output file. This is useful in case we want to close files and upload them based on a minimum size threshold. Since ParquetWriter keeps everything in memory and only writes it out to disk at the very end when writer is closed, it is not possible to have an estimate of the output file size before closing the writer.

Based on Parquet documentation, the data is written into memory object in the final format, meaning that the size of the object in memory is the very close to the final size on disk. it would be great if you can expose the current size of the parquetWriter object in memory. It is true that such a size will be different than the final output size because of adding the schema and other metadata at the end of the file but it still gives a close estimation of the output file size that will be very useful when reading/writing streams.

**Reporter**: [Reza Shiftehfar](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=reza79)

_{**Note**: *This issue was originally created as [PARQUET-209](https://issues.apache.org/jira/browse/PARQUET-209). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

首先跟踪 ParquetWriter 在 close 前的内存中输出生命周期，并确定可以在哪里公开其当前大小。检查现有的 writer 测试，并将报告的估计值与最终文件大小进行比较；完成的标准是调用方可以在关闭 writer 前获得有用的大小估计值。

由索引模型根据 Issue 内容生成。