feat(hugging_face): Add support for multiple models and dimensions

[bricesanchez]

Hello! Thank you for this awesome gem!

I'm currently playing with it and i've seen Hugging face ruby gem can now support custom embedding models:

see: alchaplinsky/hugging-face@bee85a4

I've added the ability to change the embedding model and did some clean up in the class.

[andreibondarev]

@bricesanchez Thank you for the PR, looks like the specs are failing.

[bricesanchez]

@andreibondarev You're right!

It looks like elasticsearch class looks like for the LLM dimensions (lib/langchain/vectorsearch/elasticsearch.rb:107).
And with my change, it breaks.

But it looks like there is no dimension mention in the hugging_face gem.

I can re-add it for simplicity.

What do you think?

[andreibondarev]

@bricesanchez Take a look at how we do it in the Ollama integration:

langchainrb/lib/langchain/llm/ollama.rb

Lines 53 to 59 in b3a1b65

	def default_dimensions
	# since Ollama can run multiple models, look it up or generate an embedding and return the size
	@default_dimensions ||=
	EMBEDDING_SIZES.fetch(defaults[:embeddings_model_name].to_sym) do
	embed(text: "test").embedding.size
	end
	end

[bricesanchez]

@andreibondarev, I've made the changes, don't hesitate if you have any comments!

[andreibondarev]

@bricesanchez Thank you! Left you a comment.

[andreibondarev]

@bricesanchez I'm going to review it shortly.

[andreibondarev]

@bricesanchez Thank you for the PR! Looks great!

[bricesanchez]

Thank you @andreibondarev!