Ensure that Azure Data Explorer uses double encryption in Azure Kusto Cluster

Azure Data Explorer in Kusto Cluster does not have double encryption enabled, this may compromise sensitive data.

In Azure Console -

1. Open the Azure Portal and go to Data Explorer Clusters.
2. Choose the cluster you wish to edit.
3. Under Security + Networking, select Security.
4. Set Double Encryption to On.
5. Select Save.

In Terraform -

1. In the azurerm_kusto_cluster resource, set double_encryption_enabled to true.

References:
https://learn.microsoft.com/en-us/azure/data-explorer/cluster-encryption-double?WT.mc_id=Portal-Microsoft_Azure_Kusto&tabs=portal
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/kusto_cluster#double_encryption_enabled