Given enhancement - https://github.com/openshift/enhancements/pull/1481

Design Review Doc: https://docs.google.com/document/d/1-XuHN6_jvJMLULFwwAThfIcHqY32s32lU6m4bx7BiBE/edit

We want to allow the relevant APIs to pin images and make sure those don't get garbage collected.

Here is a summary of what will be required:

1. CRI-O will need to be changed so that it doesn't remove pinned images, regardless of the version_file_persist setting.
2. Add the new PinnedImageSet custom resource definition to the API.
3. Initial proposal: #1609
4. Add a new PinnedIMageSetController to the machine-config-controller.
5. Add the logic to pin and pull the images to the machine-config-daemon.
6. Update the documentation of recovery procedures to explain that pinned images shouldn't be removed.