Set envelope default message by type using resources

Added "Please read and confirm this document" to resource files and updated resource class. Replaced Envelope constructor with WithDefaultMessage extension method to set default message based on EnvelopeTypeId. Updated controller and editor form to use this method. Cleaned up imports and comments.

EnvelopeGenerator.Domain/Entities/Envelope.cs

@@ -14,12 +14,7 @@ namespace EnvelopeGenerator.Domain.Entities
     [Table("TBSIG_ENVELOPE", Schema = "dbo")]
     public class Envelope
     {
-        public Envelope()
-        {
-#if NETFRAMEWORK
-            Message = My.Resources.Envelope.Please_read_and_sign_this_document;
-#endif
-        }
+        // removed: WithDefaultMessage()
 
         // TODO: * Check the Form App and remove the default value
         [Key]