* Add get active slot /slots/{slotId} to REST api, use utils/json
- Add endpoint /slots/{slotId} to get an active SalesAgent from the Sales module. Used in integration tests to test when a sale has reached a certain state. Those integration test changes will be included in a larger PR, coming later.
- Add OpenAPI changes for new endpoint and associated components
- Use utils/json instead of nim-json-serialization. Required exemption of imports from several packages that export nim-json-serialization by default.
* Only except `toJson` from import/export of chronicles