Write helper for available models and api versions

[AlbertRapp]

It's quite cumbersome to look into the API docs to figure out what models are available. Would be nice to have something like list_models(vendor) that displays the available chat models of a vendor.

Same thing for api_version.

[AlbertRapp]

For openAI: https://platform.openai.com/docs/api-reference/models/list

For Mistral: https://docs.mistral.ai/api/#operation/listModels

For Anthropic there doesn't seem to be an API that lists the available models. Hardcoding the values and providing a a link is the best I can do I guess https://docs.anthropic.com/claude/docs/models-overview#get-started-with-claude