Add vmap support for PyTorch operators

[zou3519]

We're looking for more motivated open-source developers to help build out functorch (and PyTorch, since functorch is now just a part of PyTorch). Below is a selection of good first issues.

• [x] https://github.com/pytorch/pytorch/issues/91174
• [x] https://github.com/pytorch/pytorch/issues/91175
• [x] https://github.com/pytorch/pytorch/issues/91176
• [x] https://github.com/pytorch/pytorch/issues/91177
• [x] https://github.com/pytorch/pytorch/issues/91402
• [x] https://github.com/pytorch/pytorch/issues/91403
• [x] https://github.com/pytorch/pytorch/issues/91404
• [x] https://github.com/pytorch/pytorch/issues/91415
• [ ] https://github.com/pytorch/pytorch/issues/91700

In general there's a high barrier to developing PyTorch and/or functorch. We've collected topics and information over at the PyTorch Developer Wiki

[msaroufim]

Would you to happen to have more? Would love to grab something but all the existing issues seem taken

[zou3519]

@msaroufim I added some more to the list, thanks for your interest