MVP example for model inference and saving predicted results.

[pdogra89]

Sliding window inference
Writing segmentation as a nifti image (Nifti image writer)
Writing classification as a json file (json writer)

[Nic-Ma]

Hi @ericspod ,

Would you like to add this part to your existing 3D segmentation example? Or create a new example?
I suggest to unify most logics of the evaluation and validation processes.
Thanks.

[pdogra89]

Eric, Wenqi and Nic would align on Design and what can be leveraged from NiftyNet/Clara/Eric's mechanisms. Eric to put together a PR.