Add Directory wrapper to track per-query IO counters [LUCENE-8884]

Lucene's IO abstractions (`Directory, IndexInput/Output`) make it really easy to track counters of how many IOPs and net bytes are read for each query, which is a useful metric to track/aggregate/alarm on in production or dev benchmarks.

At my day job we use these wrappers in our nightly benchmarks to catch any accidental performance regressions.

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Migrated from [LUCENE-8884](https://issues.apache.org/jira/browse/LUCENE-8884) by Michael McCandless (@mikemccand), updated Sep 04 2019
Attachments: [LUCENE-8884.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-8884/LUCENE-8884.patch) (versions: 2)