re-evalulate magicgui + pydantic

[chrishavlin]

latest magicgui includes support for pydantic, might be able to simplify alot of the custom pydantic object traversal happening here.

[chrishavlin]

update: magicgui is very close to being able to recursively traverse objects. see https://forum.image.sc/t/building-a-napari-widget-from-a-pydantic-model/90257

Might be able to use that new build_widget function after registering the nested pydantic classes with magicgui.