Add epoch to pytorch_lightning adaptor

[we-taper]

🚀 Feature

Add epoch to aim's pytorch_lightning adaptor, whenever it's available.

Pitch

Often the current epoch number is available as a metric from logs sent by pytorch_lightning. If we can extract this epoch to pass it to Aim's logger, then people can set x axis as epoch in Aim's metric explorer. This helps comparing logged values across different experiments with possibly different batch sizes.

Additional context

I am interested to implement this (should be as simple as adding epoch=metric.get('epoch', None) in the adaptor), but I am not sure if this is interesting for you guys? Also, I'd think it's better to keep 'epoch' inside metric still (not del metric['epoch'] after getting it).

[SGevorg]

Hey @we-taper thanks for reporting, sorry for the late reply. 🙏 Would you be interested to contribute this one?