Enable torch.cuda.nvtx typechecking (#43443)
Summary:
Add pyi file covering torch._C.nvtx submodule
Fixes https://github.com/pytorch/pytorch/issues/43436
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43443
Reviewed By: ezyang
Differential Revision: D23280188
Pulled By: malfet
fbshipit-source-id: 882860cce9feb0b5307c8b7c887f4a2f2c1548a2
