Workarounds for cudnn_batch_norm with TorchRefsNvfuserCapabilityMode (#86796)
This PR adds workarounds to support AOT Autograd's graphs containing `aten.cudnn_batch_norm` and `aten.cudnn_batch_norm_backward` with `TorchRefsNvfuserCapabilityMode`.
The problem with the decomposition of `aten.cudnn_batch_norm` is that it uses a `new_empty` call that is not supported by nvFuser and we are conservative with lowering functions to nvprims by default.
The problem with the decomposition of `aten.cudnn_batch_norm_backward` is described here https://github.com/pytorch/pytorch/pull/86115#issue-1394883782, but changing the decomposition directly in that PR makes many tests fail.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86796
Approved by: https://github.com/mruberry
