feat: add IP formatting function for Azure Storage Firewall

[conraddd]

Summary

• Adds format_ips_for_azure_storage() to the Azure Function App example in docs/firewall-automation-guide.md — expands /31 and /32 CIDRs into individual host IPs before applying Storage Account network rules; leaves wider prefixes as CIDR strings. And wires the helper into the optional Storage Account sync path
• Updates the doc on how Azure SDK handles the /31 and /32 CIDRs

Why

Azure Storage network rules do not accept the /31 and /32 as CIDR strings, even in the Azure SDK

This is documentation-only (same scope as the guide's existing Function App sample). The Terraform CIDR module from PR #2 is unchanged — customers who use source_files with -outbound.txt and write their own azurerm_storage_account_network_rules may still need equivalent /31//32 handling in their apply logic; this PR shows the pattern in the Azure automation walkthrough.

Test plan

• Test behavior locally (Azure uksouth outbound):
  • 172.186.31.34/31 → 172.186.31.34, 172.186.31.35
  • 51.140.203.27/32 → 51.140.203.27

Backward compatibility

• No changes to published TXT feeds, update_outputs.py, or terraform/.
• Existing combined and direction-scoped URLs are unchanged; this only improves the copy-paste Azure Function example and its Storage Account notes.