Add the correct prediction channels in napari interface

[Buglakova]

Hello,

When I use UNet prediction in Napari, the layers that are added are not consistent with the choices. For example, I know that generic_plant_nuclei_3D has both boundary and nuclei channels but if I choose "All" in the menu, it only adds the nuclei channel. As a result, I can't run the postprocessing step. I tried a few models and for all of them only one channel was added.

[qin-yu]

@Buglakova I'm fixing it in #173