Add DocResult property and update EnvelopeController

- Introduced a new `DocResult` property in `EnvelopeDto.cs` and `Envelope.cs` for handling binary data.
- Rearranged properties in `EnvelopeDto.cs` for better organization.
- Modified `EnvelopeController` to return a collection of envelopes instead of a single envelope.

EnvelopeGenerator.Domain/Entities/Envelope.cs

@@ -86,6 +86,9 @@ namespace EnvelopeGenerator.Domain.Entities
         [Column("TFA_ENABLED", TypeName = "bit")]
         public bool TFAEnabled { get; set; }
 
+        [Column("DOC_RESULT", TypeName = "varbinary(max)")]
+        public byte[]? DocResult { get; init; }
+
         /// <summary>
         /// The sender of envelope
         /// </summary>