Flattening retains empty testsets with new properties

[omus]

Mostly convenient for testing purposes. Overall I think this behavior is more intuitive in that if someone sets a property on a testset they would expect to appear in the generated report.

[omus]

Cherry-picked the commits from #99 to assist in debugging the CI failure by eliminating those errors. Not sure about why it appears the "test_with_properties.txt" reference works fine locally but breaks on CI currently.

Update: I forgot to update the total test count in the pre-1.7 reference file.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.46%. Comparing base (f228a7a) to head (6f90b10).
Report is 1 commits behind head on master.

❗ Current head 6f90b10 differs from pull request most recent head c9d5f09. Consider uploading reports for the commit c9d5f09 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #102      +/-   ##
==========================================
- Coverage   94.69%   91.46%   -3.24%     
==========================================
  Files           7        7              
  Lines         547      527      -20     
==========================================
- Hits          518      482      -36     
- Misses         29       45      +16     

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[oxinabox]

Seems good to me. I just realized you are part of the org.
So feel free to merge this when you are happy

[omus]

Looks like the CI jobs are stuck on CodeCov reporting. Maybe updating to use the latest GHA will allow the jobs to complete.