Update repro get_files to handle regression reports

[kananb]

Summary of the Pull Request

#3338
onefuzz repro get_files only handles reports and not regression_reports.

PR Checklist

• Applies to work item: #xxx
• CLA signed. If not, go over here and sign the CLI.
• Tests added/passed
• Requires documentation to be updated
• I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

Info on Pull Request

Adds logic for checking that the fields expected in a normal report exist before falling back on fields expected from a regression report. An error is logged otherwise.

Validation Steps Performed

How does someone test & validate?

[codecov-commenter]

Codecov Report

Merging #3340 (e5adcdf) into main (62c3f07) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #3340   +/-   ##
=======================================
  Coverage   31.83%   31.83%           
=======================================
  Files         307      307           
  Lines       37358    37358           
=======================================
  Hits        11894    11894           
  Misses      25464    25464