Adding pytorch benchmark?

[thipokKub]

Pytorch just release early support for Metal Performance Shader (mps) device, from official blog. I think this issue might be off-topic as the project name is literally tf-metal-experiments, but it would be nice to have baselines comparison between both Tensorflow and Pytorch performance benchmark

But noted that (at least, as of right now) a noticeable performance gain seems to come from M1 Ultra chip, and with large enough batch size, and a lot of operation are not supported (see pytorch/pytorch#77764)