[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.*}