Add missing metadata in the bundle, helper script for certification

[lucacome]

• Adds metadata in the bundle required for Red Hat certification
• Adds helper script that retrieves SHA for the docker images (needed for the certification). The images need to have the SHA instead of a tag, and the creation date of the Operator container.

Ideally, we could have the script fill out the fields with the required data, but yq has a bug that changes all the formatting of the yaml file https://github.com/mikefarah/yq#known-issues--missing-features