Concurrent read micro benchmarks

parquet-benchmarks only contain read and write benchmarks with a single thread.
I add concurrent Parquet file scans like typical data-parallel computing.

**Reporter**: [Takeshi Yoshimura](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=tyos)
#### PRs and other links:
- [PR440](https://github.com/apache/parquet-mr/pull/440)

_{**Note**: *This issue was originally created as [PARQUET-1174](https://issues.apache.org/jira/browse/PARQUET-1174). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Start by reviewing the existing parquet-benchmarks read and write benchmarks and PR440, which is linked from the issue. The requested outcome is concurrent Parquet file scan micro-benchmarks that represent data-parallel computing rather than only single-threaded reads.

Written by the indexing model from the issue text.