Add buyer/seller IDs to CSV fields

[b-r-u]

Previously, the CSV exports used to only contain the names of the
trading parties. Including the unique IDs makes it easier to connect
CSV rows to the corresponding entities.

[CLAassistant]

All committers have signed the CLA.

[hannesdiedrich]

Thanks a lot for your contribution and re-adding the buyer and seller ids to the exported CSV files. We will leave our reviews soon.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.58%. Comparing base (09a0204) to head (d7f4117).
Report is 1037 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #302   +/-   ##
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  Coverage   52.58%   52.58%           
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  Files          50       50           
  Lines        3041     3041           
  Branches      586      586           
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  Hits         1599     1599           
  Misses       1371     1371           
  Partials       71       71           

[hannesdiedrich]

LGTM

[b-r-u]

Thanks for taking the time to review this external PR! Should I update the branch with the newest changes from master?

[Hassan754]

Thanks for taking the time to review this external PR! Should I update the branch with the newest changes from master?

Yes, before pushing a PR to master it should be up to date, let us know when you're done so we can perform another round of review

[b-r-u]

@Hassan754 Alright, there were no merge conflicts with master. The files I edited remained untouched since my commit.