Update AddedWho property in EnvelopeReceiverReadOnly

Modified the `AddedWho` property to use `nvarchar(250)`
and increased the string length constraint from 100 to 250
characters, allowing for more extensive data storage.

EnvelopeGenerator.Domain/Entities/EnvelopeReceiverReadOnly.cs

@@ -33,9 +33,9 @@ namespace EnvelopeGenerator.Domain.Entities
         [Required]
         public DateTime DateValid { get; set; }
 
-        [Column("ADDED_WHO")]
+        [Column("ADDED_WHO", TypeName = "nvarchar(250)")]
         [Required]
-        [StringLength(100)]
+        [StringLength(250)]
         public string AddedWho { get; set; }
 
         public Receiver Receiver { get; set; }