LCO/OCS handle `extra_fields`

[Fingel]

The request models for LCO/OCS still have some free-form dictionary fields with no local validation: the various extra_data fields. These are dict[Any, Any] and it's not clear to me how you are supposed to know how to fill most of them out without using the Observation Portal front-end to build your request for you.

The /api/instruments/ endpoint does contain validation rules for some of these fields per instrument in the form of a cerberbus DSL. It might be possible to parse these rules in order to generate the correct fields in Pydantic to remove the need for extra_data.

It will certainly be a challenge!

[jchate6]

From Slack:
Well I gave the extra_params generation another honest go today, couple hours in and there's no clear/clean path to implement it for the OCS. /api/instruments and cerberus are just too custom to achieve a good mapping. Aeonlib users will simply need to do online validation to make sure what they input into extra_param fields is correct. Where they look up what parameters extra_params accepts I'm still not sure. Sadge