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/ReceiverController.cs

@@ -1,5 +1,5 @@
-using DigitalData.Core.API;
-using DigitalData.Core.DTO;
+using DigitalData.Core.Abstraction.Application.DTO;
+using DigitalData.Core.API;
 using EnvelopeGenerator.Application.Contracts.Services;
 using EnvelopeGenerator.Application.DTOs.Receiver;
 using EnvelopeGenerator.Application.Receivers.Queries.Read;
@@ -19,6 +19,7 @@ namespace EnvelopeGenerator.GeneratorAPI.Controllers;
 [Route("api/[controller]")]
 [ApiController]
 [Authorize]
+[Obsolete("Use MediatR")]
 public class ReceiverController : CRUDControllerBaseWithErrorHandling<IReceiverService, ReceiverCreateDto, ReceiverReadDto, ReceiverUpdateDto, Receiver, int>
 {
     /// <summary>
@@ -94,4 +95,4 @@ public class ReceiverController : CRUDControllerBaseWithErrorHandling<IReceiverS
         return base.GetById(id);
     }
     #endregion
-}
+}