Deprecate controllers/services; simplify generics

Added `[Obsolete("Use MediatR")]` attributes to various controller and service classes to indicate deprecation in favor of MediatR. Simplified generic type constraints in `CRUDControllerBase` and related files by removing `IUnique<TId>`. Improved structure and documentation in `CSPMiddleware.cs`. Introduced new extension methods in `EntityExtensions.cs` for safer retrieval of 'Id' properties. Removed `IUnique.cs` interface and updated project dependencies in `DigitalData.Core.Application.csproj` for caching. Overall, these changes enhance code maintainability and clarity.

DigitalData.Core.Application/Interfaces/ICRUDService.cs

@@ -1,10 +1,10 @@
-using DigitalData.Core.Abstractions;
-using DigitalData.Core.Application.DTO;
+using DigitalData.Core.Application.DTO;
 
 namespace DigitalData.Core.Application.Interfaces
 {
+    [Obsolete("Use MediatR")]
     public interface ICRUDService<TCreateDto, TReadDto, TEntity, TId> : IReadService<TReadDto, TEntity, TId>
-        where TCreateDto : class where TReadDto : class where TEntity : class, IUnique<TId>
+        where TCreateDto : class where TReadDto : class where TEntity : class
     {
         /// <summary>
         /// Asynchronously creates a new entity based on the provided <paramref name="createDto"/> and returns the identifier of the created entity wrapped in a <see cref="DataResult{TId}"/>.
@@ -21,6 +21,6 @@ namespace DigitalData.Core.Application.Interfaces
         /// </summary>
         /// <param name="updateDto">The updateDTO with updated values for the entity.</param>
         /// <returns>An Result indicating the outcome of the update operation, with an appropriate message.</returns>
-        Task<Result> UpdateAsync<TUpdateDto>(TUpdateDto updateDto) where TUpdateDto : IUnique<TId>;
+        Task<Result> UpdateAsync<TUpdateDto>(TUpdateDto updateDto);
     }
 }