Add vignette on 'Visualization utilities'

[cregouby]

As a port of Visualization Utilities

[DerrickUnleashed]

@cregouby Could we have a more detailed explanation of the requirements?
Specifically, what exactly needs to be implemented in the R/vision_utils.R file.

[cregouby]

Sure @DerrickUnleashed !

The intent here is to have a vignette in the torchvision package (and website) that mimic the content of the given pytorch vision document.
You have to create a Rmd file in the /vignettes/ folder that is a step by step guide for the same tasks (on the same images ? ) as in the given doc.
Actually, nothing is related to R/vision_utils.R.
Please let me know if you need more.