Enabled to set perform snat to always when PrivateRange is set to 255.255.255.255/32 (Azure#20497)

Co-authored-by: Gizachew Eshetie <v-geshetie@microsoft.com>

Author: Gizachew-Eshetie

src/Network/Network/ChangeLog.md

@@ -19,6 +19,7 @@
 --->
 
 ## Upcoming Release
+* Fixed a bug that does not enable to set Perform SNAT to Always
 * Fixed the incorrect type of `-TotalBytesPerSession` in `New-AzNetworkWatcherPacketCapture`
 
 ## Version 5.3.0

src/Network/Network/Models/AzureFirewallPolicy/PSAzureFirewallPolicy.cs

@@ -122,7 +122,7 @@ private void ValidateMaskedIpAddress(string ipAddress)
             var splittedIp = split[0].Split('.');
             var ip = Int32.Parse(splittedIp[0]) << 24;
             ip += (Int32.Parse(splittedIp[1]) << 16) + (Int32.Parse(splittedIp[2]) << 8) + Int32.Parse(splittedIp[3]);
-            if (ip << bit != 0)
+            if ((ip << bit != 0) && (ip << bit != -1))
                 throw new AzPSArgumentException(String.Format(Resources.InvalidPrivateIPRangeUnmaskedBits, ipAddress), nameof(ipAddress), ErrorKind.UserError);
         }