* First stab
* Delivery API client credentials + a little refactor to ensure unique client IDs
* Introduce user type
* Support user type in the Management API
* Clean up TODOs
* Update API user last login date when issuing a token
* Better error reporting for mismatched user types
* Do not allow password change or reset for API users
* Update OpenApi.json
* Revert change
* Remove obsolete comment
* Make applicable classes abstract or sealed
* Review changes
* Add endpoint for retrieving all user client IDs