[FEATURE] Add ZenNAS

[MichaelMonashev]

https://github.com/idstcv/ZenNAS faster, bigger and more precise versions of GPU-Efficient-Networks ( https://github.com/rwightman/pytorch-image-models/blob/master/timm/models/byobnet.py ).

[rwightman]

@MichaelMonashev thanks, I'll tackle it at some point but low priority. It uses different blocks from the others so need to define those, and working with their model definitions is really fiddly.