Deprecate services in favor of MediatR integration

This commit introduces the `[Obsolete("Use MediatR")]` attribute to various service fields and methods across multiple controllers and extension classes, signaling a transition to MediatR for handling requests and commands.

Key changes include:
- Marking `IEnvelopeService`, `IEnvelopeReceiverService`, and `IEnvelopeTypeService` as obsolete in their respective controllers.
- Updating `AddEnvelopeGeneratorInfrastructureServices` to utilize `IRepository`.
- Refactoring `AddCommandManagerRunner` and `CreateHost` methods to indicate obsolescence.
- Replacing `DigitalData.Core.DTO` with `DigitalData.Core.Abstraction.Application.DTO` in using directives.

These changes modernize the codebase and improve command and query handling while cleaning up service dependencies.

EnvelopeGenerator.GeneratorAPI/Controllers/EnvelopeReceiverController.cs

@@ -1,5 +1,5 @@
 using AutoMapper;
-using DigitalData.Core.DTO;
+using DigitalData.Core.Abstraction.Application.DTO;
 using EnvelopeGenerator.Application.Contracts.Services;
 using EnvelopeGenerator.Application.Contracts.SQLExecutor;
 using EnvelopeGenerator.Application.DTOs.Receiver;
@@ -31,6 +31,7 @@ public class EnvelopeReceiverController : ControllerBase
 {
     private readonly ILogger<EnvelopeReceiverController> _logger;
 
+    [Obsolete("Use MediatR")]
     private readonly IEnvelopeReceiverService _erService;
 
     private readonly IMediator _mediator;
@@ -56,6 +57,7 @@ public class EnvelopeReceiverController : ControllerBase
     /// <param name="erExecutor"></param>
     /// <param name="documentExecutor"></param>
     /// <param name="csOpt"></param>
+    [Obsolete("Use MediatR")]
     public EnvelopeReceiverController(ILogger<EnvelopeReceiverController> logger, IEnvelopeReceiverService envelopeReceiverService, IMediator mediator, IMapper mapper, IEnvelopeExecutor envelopeExecutor, IEnvelopeReceiverExecutor erExecutor, IDocumentExecutor documentExecutor, IOptions<ConnectionString> csOpt)
     {
         _logger = logger;
@@ -82,6 +84,7 @@ public class EnvelopeReceiverController : ControllerBase
     /// <response code="500">Ein unerwarteter Fehler ist aufgetreten.</response>
     [Authorize]
     [HttpGet]
+    [Obsolete("Use MediatR")]
     public async Task<IActionResult> GetEnvelopeReceiver([FromQuery] ReadEnvelopeReceiverQuery envelopeReceiver)
     {
         var username = User.GetUsernameOrDefault();
@@ -123,6 +126,7 @@ public class EnvelopeReceiverController : ControllerBase
     /// <response code="500">Ein unerwarteter Fehler ist aufgetreten.</response>
     [Authorize]
     [HttpGet("salute")]
+    [Obsolete("Use MediatR")]
     public async Task<IActionResult> GetReceiverName([FromQuery] ReadReceiverNameQuery receiver)
     {
         return await _erService.ReadLastUsedReceiverNameByMailAsync(receiver.EmailAddress, receiver.Id, receiver.Signature).ThenAsync(