Add Pix2Pix

[aniketmaurya]

🚀 Feature

Pix2Pix is a really good example of image-to-image translation network and should be included in Lightning.

Motivation

Currently Lightning doesn't have Pix2Pix model implemented. As it is a good starting example for anyone learning GANs, it should be easily accessible for training and experimenting with custom dataset.

Pitch

I would like to take the responsibility of implementing Pix2Pix in Lightning.

Alternatives

Many good examples are already available in PyTorch. For example- https://github.com/mrzhu-cool/pix2pix-pytorch

[github-actions]

Hi! thanks for your contribution!, great first issue!

[akihironitta]

@aniketmaurya Thank you for your suggestion! It'd be great to have this model in Bolts!