Add quantized CLIP

[rockerBOO]

I was wanting to test quantization for CLIP for use in WASM and wrote this for my own but wanted to upstream it.

For making the quantized version, I have a fork of clip.cpp which uses the hugging face keys to match the original model.

https://github.com/rockerBOO/clip.cpp/tree/hf-format

I am proposing this in a limited scope currently to gauge interest, but I can provide quantized models for testing if this PR is desired.

If anything needs updating or fixed, let me know.

Thank you.