is there interest in ggml_unfold_1d ?

[balisujohn]

So unfold is an op that PyTorch supports that is a little bit hard to explain concisely but is explained here.

https://stackoverflow.com/questions/53972159/how-does-pytorchs-fold-and-unfold-work

I need it for tortoise.cpp, so as usual I will be implementing it anyway, and I'm happy to upstream it if desired. I'm still exploring implementation details but I'll post a PR once a passable draft is ready.