Allows saving luz fitted models to the disk. Objects can be loaded back with
luz_load().
luz_save(obj, path, ...)an object of class 'luz_module_fitted' as returned by
fit.luz_module_generator().
path in file system so save the object.
currently unused.
The ctx is naively serialized. Ie, we only use saveRDS() to serialize it.
Don't expect luz_save to work correctly if you have unserializable objects
in the ctx like torch_tensors and external pointers in general.
Other luz_save:
luz_load()