Supporting CPC-type games

[mbaroni]

Is your proposal related to a problem?

Discriminative emergence games are very close to the idea of contrastive predictive coding in computer vision, and it would be cool to support code for comparative experiments in EGG, in particular along the lines of https://arxiv.org/abs/1905.09272

Describe the solution you'd like to have implemented

Add code to support experiments with learning image representations using a discrete channel communication game.

[eugene-kharitonov]

Seems like a near duplicate of https://github.com/facebookresearch/EGG/issues/185

[robertodessi]

Closing as it seems a duplicate. @mbaroni feel free to reopen if we are missing something