Automation of Google Groups maintenance for k8s-infra permissions

• Edit groups.yaml to add a new group or update an existing group
• All groups MUST start with "k8s-infra-" prefix for the reconcile.go to work
• Use make run to dry run the changes
• Use make run -- --confirm if the changes suggested in the previous step looks good

Note:

• To add new git-crypt collaborators, use the git-crypt add-gpg-user command. See example steps in: https://guyrking.com/2018/09/22/encrypt-files-with-git-crypt.html