Refactor backend -> model

[rmitsch]

Description

Refactor to switch from a backend to a model paradigm.
Todos:

• Readme updates
• Update Streamlit demo

Types of change

Checklist

• I confirm that I have the right to submit this contribution under the project's MIT license.
• I ran all tests in tests and usage_examples/tests, and all new and existing tests passed. This includes
  • all external tests (i. e. pytest ran with --external)
  • all tests requiring a GPU
• My changes don't require a change to the documentation, or if they do, I've added all required information.

[rmitsch]

Mostly looks good to me! Let's start wrapping this up? Raphael can you update the readme & double check the usage examples, and maybe write a short "migration" guide we can link to?

Added migration guide and one last adjustment (name has to be specified explicitly for LangChain models now outside of the config dict to be more consistent with other models) in 502697f.

Running one last round of tests currently.

[svlandeg]

We can't try to catch those specific errors from confection, to provide a more specific/helpful warning in spacy-llm for those specific cases? Like if there's an llm.backend config section - couldn't we even check that up-front in some cases?

I wouldn't know where to. Maybe I misunderstand something, but IMO the first thing that happens is that @Language.factory is run, including the config validation. I don't see how we can precede that or even catch that the resulting error?

[Edit] Well, I guess we can build our own @Language.factory that essentially calls spaCy's @Language.factory, but does those checks before. Not sure we really want that.

Yea, I guess you're right. We could make it a "FAQ" in the discussions forum so at least people will (hopefully) easily find the solution when they get that specific error?

[svlandeg]

The readme should somewhere have a list of all models available from llm_models, right? (at least for the non-langchain-ones)

[svlandeg]

This is looking really good, thanks for pushing this one true Raphael! 🙏

I mainly had some smaller comments, typo's etc. Feel free to merge once you're ready.