Add NanoGPT as an API Provider

[Salloxy]

I'm using NanoGPT (https://nano-gpt.com/api) through OpenAI Compatible API, would be nice to see them as a separate API Provider since they currently provide virtually all models at the cheapest price (both subscription and API). If someone is actually going to implement this I'd also request adding "GET /api/v1/models" for the models list so they're always up to date. Thanks!