Litelm: Litellm Without the Bloat

First commit was 2 weeks ago. A clean-room rewrite of only the most essential APIs of litellm.

Was annoyed that DSPy was about 250 MB big. Mostly due to litellm being bloated and numpy. In order to create dspy-lite [1], I had to create a lighter litellm and make numpy optional (only essential for embeddings).

Made the lighter litellm litelm by selecting the parts of litellm's test suite that mattered and build it back to match litellms API.