[Examples] Implement a training script for InstructPix2Pix

[sayakpaul]

We already have the pipeline: #2040

Given how interesting results it can generate, I think it would be greatly beneficial to add an example script showing how one can perform the underlying training of InstructPix2Pix -- another useful way to fine-tune Stable Diffusion :)

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the contributing guidelines are likely to be ignored.

[sayakpaul]

Working on it.