Add File Size to Parquet Metrics

[stanbrub]

Currently, we collect read/write rates for the Parquet Benchmarks. So for the multi-column tests that are meant to allow comparison between codecs (e.g. snappy, gzip), Shivam would like to see resulting parquet file size as well. (Stan would like to see a more generic way to pull in extra metrics to adhoc runs. So this is a good fit.)

This has been done manually before, but it makes sense to automate it, since there are more metrics of interest (like installation size, memory usage, etc) that are not being shown in a meaningful or obvious way.

• Add file size metric collection to the FileTestRunner (this should be relatively straightforward)
• Improve the adhoc snippet to allow selection of a metric by property name
  • Some metrics may be unique to certain benchmarks
  • Ensure proper null handling if the specified metrics are not present
• Pull file size metric in beside the rate column in the result table for the run sets

[stanbrub]

There is a metric called 'data.file.size' that has been added for the Parquet tests. Queries have been updated to allow metrics that are null for some and provided for others. Also, the adhoc snippet now has a way for the user to specify metric names that are pulled in as columns beside other columns like op_rate.