Ensure Master authorized networks are set to Enabled on Kubernetes Engine Clusters

Authorized networks are a way of specifying a restricted range of IP addresses that are permitted to access your container cluster's Kubernetes master endpoint. Kubernetes Engine uses both Transport Layer Security (TLS) and authentication to provide secure access to your container cluster's Kubernetes master endpoint from the public internet. This provides you the flexibility to administer your cluster from anywhere; however, you might want to further restrict access to a set of IP addresses that you control. You can set this restriction by specifying an authorized network.