Affected: Go: github.com/kyverno/kyverno

### Summary A kyverno ClusterPolicy, ie. "disallow-privileged-containers," can be overridden by the creation of a PolicyException in a random namespace.

### Details By design, PolicyExceptions are consumed from any namespace. Administrators may not recognize that this allows users with privileges to non-kyverno namespaces to create exceptions.

### PoC 1. Administrator creates "disallow-privileged-containers" ClusterPolicy that applies to resources in the namespace "ubuntu-restricted" 2. Cluster user creates a PolicyException object for "disallow-privileged-containers" in namespace "ubuntu-restricted" 3. Cluster user creates a pod with a privileged container in "ubuntu-restricted" 4. Cluster user escalates to root on the node from the privileged container

### Impact Administrators attempting to enforce cluster security through kyverno policies, but that allow less privileged users to create resources