Export system public (and private) information

I'd like an function that per month per association that can export all the drinks, so that it is easier to have a look per drink what was bought and what was sold. I have an example Excelsheet if you'd like to have a look at it.

The issue names no files, tests, or entry points. Start by locating how associations and drink purchases and sales are stored, then confirm the required monthly export fields and the meaning of public versus private information with the maintainer. Done means the requested per-association, per-month drink export matches the supplied Excel example, which is not attached here.

Written by the indexing model from the issue text.