[parquet-tools] dump command shows binary values differenty than the cat or head commands

`parquet-tools dump` shows binary values as strings, if they are valid UTF-8 sequences.

`parquet-tools cat` and `parquet-tools head` show binary values base64-encoded, regardless of whether they are valid UTF-8 sequences or not.

(If the type is annotated as UTF-8, the values are shown as strings by all of these commands.)

**Reporter**: [Zoltan Ivanfi](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=zi) / @zivanfi

_{**Note**: *This issue was originally created as [PARQUET-1347](https://issues.apache.org/jira/browse/PARQUET-1347). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

首先定位 parquet-tools 对 dump、cat 和 head 命令的实现，并比较它们如何呈现二进制值。确认现有的 UTF-8 注解行为，然后通过使用具有代表性的值检查命令输出，使未注解的二进制输出与 cat 和 head 保持一致。

由索引模型根据 Issue 内容生成。