Deprecate repositories and update service interfaces

- Marked `IEnvelopeReceiverRepository` and several repository classes as obsolete, recommending the use of `IRepository`.
- Corrected `using` directive in `IReceiverService.cs`.
- Removed `UpdateAsync` method from `IReceiverService`.
- Enhanced `ISmsSender` interface with new properties and methods.
- Updated `ReceiverCreateDto`, `ReceiverReadDto`, and `UserReceiverDto` to enforce non-nullable properties.
- Refactored `TestReceiverController` to suggest using `MediatR`.

EnvelopeGenerator.Application/DTOs/Receiver/ReceiverCreateDto.cs

@@ -18,7 +18,7 @@ public record ReceiverCreateDto
     {
         _sha256HexOfMail = new(() =>
         {
-            var bytes_arr = Encoding.UTF8.GetBytes(EmailAddress.ToUpper());
+            var bytes_arr = Encoding.UTF8.GetBytes(EmailAddress!.ToUpper());
             var hash_arr = SHA256.HashData(bytes_arr);
             var hexa_str = BitConverter.ToString(hash_arr);
             return hexa_str.Replace("-", string.Empty);
@@ -37,7 +37,7 @@ public record ReceiverCreateDto
     public string? TotpSecretkey { get; init; }
 
     /// <summary>
-    /// var bytes_arr = Encoding.UTF8.GetBytes(EmailAddress.ToUpper());<br>
+    /// var bytes_arr = Encoding.UTF8.GetBytes(EmailAddress.ToUpper());<br/>
     /// var hash_arr = SHA256.HashData(bytes_arr);
     /// var hexa_str = BitConverter.ToString(hash_arr);
     /// return hexa_str.Replace("-", string.Empty);

EnvelopeGenerator.Application/DTOs/Receiver/ReceiverReadDto.cs

@@ -4,26 +4,57 @@ using System.Text.Json.Serialization;
 
 namespace EnvelopeGenerator.Application.DTOs.Receiver;
 
+/// <summary>
+/// 
+/// </summary>
 [ApiExplorerSettings(IgnoreApi = true)]
 public class ReceiverReadDto
 {
+    /// <summary>
+    /// 
+    /// </summary>
     public int Id { get; set; }
 
-    public string EmailAddress { get; set; }
+    /// <summary>
+    /// 
+    /// </summary>
+    public required string EmailAddress { get; set; }
 
-    public string Signature { get; set; }
+    /// <summary>
+    /// 
+    /// </summary>
+    public required string Signature { get; set; }
 
+    /// <summary>
+    /// 
+    /// </summary>
     public DateTime AddedWhen { get; set; }
 
+    /// <summary>
+    /// 
+    /// </summary>
     [JsonIgnore]
     public IEnumerable<EnvelopeReceiverBasicDto>? EnvelopeReceivers { get; set; }
 
+    /// <summary>
+    /// 
+    /// </summary>
     public string? LastUsedName => EnvelopeReceivers?.LastOrDefault()?.Name;
 
+    /// <summary>
+    /// 
+    /// </summary>
     public string? TotpSecretkey { get; set; } = null;
 
+    /// <summary>
+    /// 
+    /// </summary>
     public DateTime? TfaRegDeadline { get; set; }
 
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <returns></returns>
     public override int GetHashCode()
     {
         return Id.GetHashCode();

EnvelopeGenerator.Application/DTOs/UserReceiverDto.cs

@@ -26,7 +26,7 @@ public class UserReceiverDto
     /// <summary>
     /// Gets or sets the name of the receiver.
     /// </summary>
-    public string Name { get; set; }
+    public required string Name { get; set; }
 
     /// <summary>
     /// Gets or sets the company name of the receiver.