Add xff support (#32484)

Co-authored-by: Yaara Rumney <[email protected]>

Author: yaarark

specification/network/resource-manager/Microsoft.Network/stable/2024-07-01/webapplicationfirewall.json

@@ -757,7 +757,9 @@
           "enum": [
             "ClientAddr",
             "GeoLocation",
-            "None"
+            "None",
+            "ClientAddrXFFHeader",
+            "GeoLocationXFFHeader"
           ],
           "x-ms-enum": {
             "name": "ApplicationGatewayFirewallUserSessionVariable",