The Inquiry and Donation models should be extended with a relationship to a Tracking entity. The Tracking entity should have the following fields:
Maybe the wikiLogin field could also be migrated there (in a backwards-compatible way).
At the moment all these values are lumped in the `data` field of Inquiry and Donation.
See https://github.com/wmde/FundraisingStore/issues/36 for ideas on backwards- and forwards-compatibility.
This is a cross-cutting concern for the use-cases T123044, T123043 and T123040. We need a decision if we leave the `data` field mess as it is or take the time to refactor it.