Add IsReadAndSign extension method to IEnvelope

Introduced the IsReadAndSign method to IEnvelope extensions, which returns true when EnvelopeTypeId is not 2. This allows clear differentiation between "Read and Sign" and "Read and Confirm" envelope types.

EnvelopeGenerator.Domain/Interfaces/IEnvelope.cs

@@ -11,5 +11,10 @@
         {
             return envelope.EnvelopeTypeId == 2;
         }
+
+        public static bool IsReadAndSign(this IEnvelope envelope)
+        {
+            return envelope.EnvelopeTypeId != 2;
+        }
     }
 }