Refactor namespaces and update DTO structures

Updated namespaces for DTOs and services to improve project organization. Marked several interfaces as obsolete in favor of MediatR for better request handling. Simplified `BaseUpdateDto` and other DTOs by removing `IUnique<int>` implementation. Changed return types of `CreateAsync` methods to return corresponding read DTOs. Removed reference to `DigitalData.Core.DTO` in the project file, reflecting a shift in architecture for maintainability.

DigitalData.UserManager.Application/DTOs/ModuleOfUser/ModuleOfUserUpdateDto.cs

@@ -1,6 +1,4 @@
-using DigitalData.Core.Abstractions;
-
-namespace DigitalData.UserManager.Application.DTOs.ModuleOfUser
+namespace DigitalData.UserManager.Application.DTOs.ModuleOfUser
 {
     public record ModuleOfUserUpdateDto(
         int Id,
@@ -9,5 +7,5 @@ namespace DigitalData.UserManager.Application.DTOs.ModuleOfUser
         bool? IsAdmin,
         string? Comment,
         string? ChangedWho
-    ) : IUnique<int>;
+    );
 }