Updates div to perform true division (#42907)
Summary:
This PR:
- updates div to perform true division
- makes torch.true_divide an alias of torch.div
This follows on work in previous PyTorch releases that first deprecated div performing "integer" or "floor" division, then prevented it by throwing a runtime error.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42907
Reviewed By: ngimel
Differential Revision: D23622114
Pulled By: mruberry
fbshipit-source-id: 414c7e3c1a662a6c3c731ad99cc942507d843927
