Modify Cinder admin access user policy

Issue

• Cinder policy file does not support user id syntax
• Can we specify the user_id of the admin account in /etc/cinder/policy.json so that cinder honors this syntax?
• If policy syntax left as: "context_is_admin": "role:admin" , then any user who is a project admin can view all volumes from any other user, which may not be desirable in all deployments. Would rather use: "context_is_admin": "user_id:ID-OF-ADMIN-ACCOUNT" or similar, that will support specifying the super-admin account only to have access to every volume.