Update APITemplateCreator.cs (#420)

I guess there is a bug during the creation of individual arm file per Api. Only with this new line I as able to create/update APIM for new APIs with the backendURL correctly set.

Author: sergiopaim

src/APIM_ARMTemplate/apimtemplate/Creator/TemplateCreators/APITemplateCreator.cs

@@ -224,6 +224,8 @@ public async Task<APITemplateResource> CreateAPITemplateResourceAsync(APIConfig
                 apiTemplateResource.properties.format = format;
                 apiTemplateResource.properties.value = value;
                 apiTemplateResource.properties.path = api.suffix;
+                apiTemplateResource.properties.serviceUrl = api.serviceUrl;
+               
             }
             return apiTemplateResource;
         }