Ensure that 'Public access level' is disabled for storage accounts with blob containers

Anonymous, public read access to a container and its blobs can be enabled in Azure Blob storage. It grants read-only access to these resources without sharing the account key, and without requiring a shared access signature. It is recommended not to provide anonymous access to blob containers until, and unless, it is strongly desired. A shared access signature token should be used for providing controlled and timed access to blob containers.