CU-8694fwyje pre load config(s)

[mart-r]

Separate config entries that only (truly) take effect if set before a model is loaded or initialised.

Some of these config entries are used elsewhere in the codebase as well. But most of the time it looks (at least to me) like their main use is at init/load time.

EDIT: This will also add translation layers to the configs for legacy mappings when loading the various configs (main, MetaCAT, TNER, RelCAT).

Also removed some of the unused config entries in RelCAT config.

This affects

• Normal medcat config
• Transformers NER config
• MetaCAT config
• RelCAT config

NOTE: I'm open to discussions on which config entries should stay where they were as well as which ones shouldn't be removed from RelCAT config.

PS: This might create issues downstream (i.e in tutorials and WWC). So if/when this PR will be approved, I'll look into creating PRs for those to go along with this one.

PPS: The main config's linking.subsample_after option is also unused. However, there is commented code for it to be used in context_based_linker.Linker._train so I left it in for now.