completed antiforgery implementation, improved external login claim mapping, principal construction, and user experience

Oqtane.Server/Extensions/StringExtensions.cs

@@ -14,5 +14,14 @@ namespace Oqtane.Extensions
 
             return list.Any(f => s.StartsWith(f));
         }
+
+        public static string ReplaceMultiple(this string s, string[] oldValues, string newValue)
+        {
+            foreach(string value in oldValues)
+            {
+                s = s.Replace(value, newValue);
+            }
+            return s;
+        }
     }
 }