Include a param for OpenAIProvider to look for a custom env var

[danfhernandez]

If I'm using an openai compatible api, it's likely that I've already set an api key to an environment variable. For example, GROQ_API_KEY for groq. So it would be nice to be able to do the following instead of including the API key as a prop:

<OpenAIProvider
      apiKeyEnvironmentVariable="GROQ_API_KEY"
      baseURL="https://api.groq.com/openai/v1"
    > ... 
</OpenAIProvider>