The page compressedSize printed by the ShowPagesCommand is actually uncompressedSize

It seems that the data page obtained by calling PageReader.readPage() (L122 in ShowPagesCommand) is decompressed, and the bytes obtained by DataPageV1 is decompressed.

**Reporter**: [Yujiang Zhong](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=zhongyuj) / @zhongyujiang
#### Original Issue Attachments:
- [59fa778d-d870-49f2-87f7-046e2e87ef9f.jpeg](https://issues.apache.org/jira/secure/attachment/13066545/59fa778d-d870-49f2-87f7-046e2e87ef9f.jpeg)
- [image-2024-02-07-16-48-08-016.png](https://issues.apache.org/jira/secure/attachment/13066544/image-2024-02-07-16-48-08-016.png)

_{**Note**: *This issue was originally created as [PARQUET-2427](https://issues.apache.org/jira/browse/PARQUET-2427). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

从 issue 中指出的 ShowPagesCommand 内 PageReader.readPage() 调用处开始，然后跟踪 DataPageV1 如何暴露其字节以及如何打印 compressedSize。重现该命令的页面大小输出，并确认显示的值表示解压缩后的数据；当报告的压缩大小与压缩后的页面数据匹配时，即视为完成。

由索引模型根据 Issue 内容生成。