Nvfuser guard patch
Fixes issue where CudaFusionGuard would return false on backward graph because `requires_grad` flag doesn't match.
This is due to the fact that autodiff uses GradMode switch to turn on/off requires_grad, which is not taken into consideration by nvfuser guard. We verified the implementation under `TensorType::matchTensor`.
- [x] Add python test to verify no fallback is observed
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75016
Approved by: https://github.com/eellison
