Add standardized OCI annotations to container images

[AlexGustafsson]

Add the org.opencontainers.image.source label to allow scanning tools to identify the source repository of the image. This is one of the labels that the OCI has standardized for adding metadata to images: https://github.com/opencontainers/image-spec/blob/main/annotations.md.

docker pull calico/kube-controllers
docker inspect calico/kube-controllers --format '{{ json .Config.Labels }}'

Output:

{"maintainer":"Casey Davenport <[email protected]>"}

Expected output:

{"maintainer":"Casey Davenport <[email protected]>", "org.opencontainers.image.source": "https://github.com/projectcalico/calico"}

docker pull calico/node
docker inspect calico/node --format '{{ json .Config.Labels }}'

Output:

{"description":"Calico node handles networking and policy for Calico","maintainer":"[email protected]","name":"Calico node","release":"1","summary":"Calico node handles networking and policy for Calico","vendor":"Project Calico","version":""}

Expected output:

{"description":"Calico node handles networking and policy for Calico","maintainer":"[email protected]","name":"Calico node","release":"1","summary":"Calico node handles networking and policy for Calico","vendor":"Project Calico","version":"","org.opencontainers.image.source": "https://github.com/projectcalico/calico"}