Ensure public network access is disabled for Azure Container Registry

Allowing unrestricted, public access to cloud services could open an application up to external attack. Disallowing this access is typically considered best practice.

In Azure Console -

1. Open the Azure Portal and go to the container registries console.
2. Choose the registry you wish to edit.
3. Under Settings, select Networking.
4. On the Public access tab, select Disabled.

In Terraform -

1. In the azurerm_container_registry resource, set 'public_network_access_enabled' to 'false'. By default 'public_network_access_enabled' is set to 'true'.

References:
https://learn.microsoft.com/en-us/azure/container-registry/
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/container_registry#public_network_access_enabled