Add cloud images page
This adds the cloud images page. It currently depends on the YAML manifest that we publish in the GitHub repo. Hopefully this is fine as a starting point. After the 3.13 release I'd like to migrate to doing a search using the AWS SDK and generating this on the fly with each site build.
To release 3.13 we'll just need to publish the images, update the YAML, and re-build the site.