Update EnvelopeDto.ReadOnly to use IsReadAndConfirm()

Refactored the ReadOnly property in EnvelopeDto to use the IsReadAndConfirm() extension method instead of directly checking EnvelopeTypeId. Marked the property as [Obsolete] and advised using EnvelopeExtensions.IsReadAndConfirm.

EnvelopeGenerator.Application/Common/Dto/EnvelopeDto.cs

@@ -75,10 +75,12 @@ public record EnvelopeDto : IEnvelope
     /// </summary>
     public int? EnvelopeTypeId { get; set; }
 
+    // TODO: use ReadAndConfirm property name
     /// <summary>
     /// 
     /// </summary>
-    public bool ReadOnly => EnvelopeTypeId == 2;
+    [Obsolete("Use EnvelopeExtensions.IsReadAndConfirm extension metot instead.")]
+    public bool ReadOnly => this.IsReadAndConfirm();
 
     /// <summary>
     ///