dataset and train example with dict transforms

[Nic-Ma]

Is your feature request related to a problem? Please describe.
Now we have 2 levels transforms: vanilla transforms and dict transforms, but we only have nifti_dataset and UNet training & evaluation examples based on vanilla transforms.
Need to develop another nifti_dataset and UNet examples based on dict transforms.

Describe the solution you'd like

1. Develop another dataset based on dict transforms.
2. Develop another UNet example based on dict transforms.