Add the training logic to examples/mlperf/model_train.py -> def train_resnet(): [Links](https://github.com/mlcommons/training/tree/master/image_classification) to the reference implementation for image classification. [Links](https://image-net.org/challenges/LSVRC/2012/) to the dataset. MLPerf training rules [here](https://github.com/mlcommons/training_policies/blob/master/training_rules.adoc#appendix-allowed-optimizers) --- Current Bounty: $500 Bounty Locked: #2370
