Add example for OPT model with distribution.

[qlzh727]

@fchollet, this is the draft of the OPT model inferencing with Keras distribution API (I can add the finetune parts later). Do u still have the instructions to convert the py example to colab/MD file?

This one will require 8 V100 GPU to simulate, and I think we should have A100 to properly simulate a finetuning workflow