FIX: Parse commas in CSV fields

[zachlindsey]

Summary

Fixes #3635

List of changes proposed in this PR (pull-request)

• Use the csv library to parse CSV files, so that quoted fields are correctly parsed.
• Add a delimiter field to CSVReader so that things like TSVs can be parsed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.14%. Comparing base (c46a957) to head (5e84919).
Report is 7 commits behind head on master.

❗ Current head 5e84919 differs from pull request most recent head f746c34. Consider uploading reports for the commit f746c34 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3637      +/-   ##
==========================================
- Coverage   63.15%   63.14%   -0.01%     
==========================================
  Files         308      308              
  Lines       40825    40824       -1     
  Branches     5656     5655       -1     
==========================================
- Hits        25781    25780       -1     
  Misses      14031    14031              
  Partials     1013     1013              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[effigies]

LGTM. Small cleanup to avoid escaping quotes.