Azure deployment: use AppService output IPs to restrict access

[billspat]

this is a reminder to use the appservices outbound IPs as a limit for other services, as we do with SendGrid.

To get a list of IPs that are used by the appservice outbound IPs in the azure deploy script :

az webapp show --resource-group <group_name> --name <app_name> --query outboundIpAddresses --output tsv