Add sigmoid/softmax interface for `AsymmetricUnifiedFocalLoss`

[ding3820]

Is your feature request related to a problem? Please describe.
It seems that AsymmetricUnifiedFocalLoss has not yet been updated to the latest interface like FocalLoss. It is a general loss function and we should make it easier for everyone to use. We can also allow multiple classes segmentation since it only supports binary one accordingly

Describe the solution you'd like
Follow the interface of FocalLoss. Also, we don't need to reinvent the wheel. I am sure we can use the available loss function to replace the implementation.

Describe alternatives you've considered
No

Additional context
No