Fix/447 add scope id configuration to portal (#469) (#473)

* Add ID scope to portal deployment template

* Read DPS Scope ID from Settings

* Add unit tests coverage to config handlers

src/AzureIoTHub.Portal/Server/ConfigHandler.cs

@@ -14,7 +14,7 @@ public abstract class ConfigHandler
         internal const string IoTHubConnectionStringKey = "IoTHub:ConnectionString";
         internal const string DPSConnectionStringKey = "IoTDPS:ConnectionString";
         internal const string DPSServiceEndpointKey = "IoTDPS:ServiceEndpoint";
-        internal const string DPSIDScopeKey = "IoTDPS:DPSIDScope";
+        internal const string DPSIDScopeKey = "IoTDPS:IDScope";
 
         internal const string OIDCScopeKey = "OIDC:Scope";
         internal const string OIDCAuthorityKey = "OIDC:Authority";