feat(medcat-trainer): CU-869a5rv2z: Extra fields for MedCATtery

[tomolopolis]

Extra fields needed for MedCATtery model registry project

[mart-r]

Looks alright.

Though "this version" of the trainer client is within the v2-specific trainer. There's another one in v1-specific one:
https://github.com/CogStack/cogstack-nlp/tree/main/v1/medcat-trainer/client

With that said, the client seems to actually be version agnostic. But there's a separate release workflow for either. Though they would end up in once place.

It may make sense to remove the v1/medcat-trainer/client? So that it's clear which one we're working on and so that we don't need to work on both in parallel? Or perhaps extract the client into its own folder separate from trainer altogether?
Definitely outside the scope of this PR, but just something worth noting.

[tomolopolis]

ah yeah - this is a really good point. I think just easier to remove the client from v1 trainer, rather than maintaining both / or having an old implementation elsewhere.