DiceFocalLoss does not have the option to run softmax focal loss

[ferreirafabio80]

The 'use_softmax' arg is missing in FocalLoss in the DiceFocalLoss class. See the screenshot.

[KumoLiu]

Hi @yiheng-wang-nv, I noticed you added this class previously. Do you remember why we not include the activation function for FocalLoss?