Together.AI provider

[HavenDV]

Project: LangChain.Providers.Together

• Since Together supports the official OpenAI interface, implementation is very simple using the OpenAI provider. See link for Anyscale
• You can use GPT-4 for initial implementation
• Tests are encouraged but not required. It's better to do something minimal than nothing.

References:

• https:/tryAGI/LangChain/tree/main/src/Providers/Anyscale/src

Now usage looks like:

var provider = new OpenAiProvider(
      apiKey: Environment.GetEnvironmentVariable("TOGETHER_API_KEY") ??
      throw new InconclusiveException("TOGETHER_API_KEY is not set"),
      customEndpoint: "api.together.xyz");
var llm = new OpenAiChatModel(provider, id: "meta-llama/Llama-2-70b-chat-hf");
var embeddings = new OpenAiEmbeddingModel(provider, id: "togethercomputer/m2-bert-80M-2k-retrieval");

[HavenDV]

Closed in #194