Speed up TSVFile class

[shorowit]

Pull Request Description

Speeds up the TSVFile class. When running smaller sample sizes, the initial reading of the large TSV files is the bottleneck. For e.g. 250 samples, this roughly cuts the time in half.

Checklist

Not all may apply:

• [ ] Tests (and test files) have been updated
• [ ] Documentation has been updated
  • [ ] If related to resstock-estimation, checklist includes data dictionary, source report, options saturation, options_lookup.
• [ ] Add to the changelog_dev.rst file
• [ ] openstudio tasks.rb update_measures has been run
• [ ] No unexpected regression test changes on CI (checked comparison artifacts)