Remove UserReceiver functionality and related components

This commit marks the `IUserReceiverRepository` and `IUserReceiverService` as obsolete and removes their implementations. The `UserReceiverDto`, `UserReceiver`, `UserReceiverService`, and `UserReceiverRepository` classes have been deleted, along with their mappings in the `MappingProfile`. Additionally, the `TestUserReceiverController` has been removed, reflecting the complete removal of user receiver functionality from the codebase.

EnvelopeGenerator.Domain/Entities/UserReceiver.cs

@@ -1,39 +0,0 @@
-using System.ComponentModel.DataAnnotations;
-using System.ComponentModel.DataAnnotations.Schema;
-#if NETFRAMEWORK
-using System;
-#endif
-
-namespace EnvelopeGenerator.Domain.Entities
-{
-    [Table("TBSIG_USER_RECEIVER", Schema = "dbo")]
-    public class UserReceiver
-    {
-        [Key]
-        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
-        [Column("GUID")]
-        public int Id { get; set; }
-
-        [Required]
-        [Column("USER_ID")]
-        public int UserId { get; set; }
-
-        [Required]
-        [Column("RECEIVER_ID")]
-        public int ReceiverId { get; set; }
-
-        [Required]
-        [Column("NAME", TypeName = "nvarchar(128)")]
-        public string Name { get; set; }
-
-        [Column("COMPANY_NAME", TypeName = "nvarchar(128)")]
-        public string CompanyName { get; set; }
-
-        [Column("JOB_TITLE", TypeName = "nvarchar(128)")]
-        public string JobTitle { get; set; }
-
-        [Required]
-        [Column("ADDED_WHEN", TypeName = "datetime")]
-        public DateTime AddedWhen { get; set; }
-    }
-}