Enhance Azure Data Exfil with DNS lookup

[nathanknox]

Leverage the DNS data source from the dns provider (https://registry.terraform.io/providers/hashicorp/dns/latest/docs/data-sources/dns_a_record_set) so that customers don't have to resolve their URIs (for SCC relay)

[nathanknox]

Alternatively...maybe just remove entirely in favor of service tag. Need to confirm feasibility first.

[alexott]

It's done in the Terraform examples: https://github.com/databricks/terraform-databricks-examples/blob/main/modules/adb-exfiltration-protection/firewall.tf#L26