Prototype card data export

This is not to be merged, but just to give context to the prototyping work documented under https://gitlab.developers.cam.ac.uk/uis/devops/iam/documentation/-/wikis/card/Migrating-Data-Exports-to-Card-API.

This work should be documented and tested before merged into master.

Any additional work required should either be added as follow-up issues or appended to: #1 (closed)

Completed under https://gitlab.developers.cam.ac.uk/uis/devops/iam/card-database/card-api/-/issues/44