Add LiteLLM support

[rafaelrddc]

Please do a quick search on GitHub issues first, the feature you are about to request might have already been requested.

Expected Behavior

Have an integration with LiteLLM so that it is possible to use them as a model.

Current Behavior

It is now possible to use LiteLLM using "spring-ai-openai", however the resources are somewhat limited, not allowing, for example, the use of fallbacks.