[Caffe2] Cudnn operator update

[petrex]

The goal is to review cudnn implementation of ops and implement miopen version if applicable

• affine_channel
• sigmoid/tanh
• transpose
• dropout
• depthwise_3x3_conv

[ashishfarmer]

Update:

• Affine channel -> typo. There is no Affine channel CUDNN or MIOpen operation, and C2 uses CUDA/HIP for that operation
• Sigmoid -> Done
• Tanh -> Done
• Dropout -> Not supported in MIOpen

[ashishfarmer]

Transpose conv -> done