GitLab

* Enabled Conv-Bias-ReLU fusion

The following modules are enabled using cuDNN runtime fusion:
1) Conv-Bias-ReLU (+backward)
2) Conv-Bias (+backward)
3) Conv-Bias-Mask-ReLU (+backward)

* Casts cleanup and autocast in unittest

- Remove redundant dtype casts
- Simulate the usage in the unittest by using torch.cuda.amp.autocast
Co-authored-by: Masaki Kozuki <mkozuki@nvidia.com>

* Fixed save_for_backward
Co-authored-by: Masaki Kozuki <mkozuki@nvidia.com>
Co-authored-by: root <root@luna-0277.selene.nvidia.com>