Add support for local open-source models

**Is your feature request related to a problem? Please describe.**
We want to generalise the package by supporting local OSS models as students or teachers

**Describe the solution you'd like**
We need to support OSS models (Zephyr, Mistral, LLama, Qwen etc) as teacher or student. Currently we are only relying on OpenAI, whereas the library should be generalised to local OSS models