Refactor namespaces and enhance application structure

This commit reorganizes namespaces from `DigitalData.Core.Abstractions` and `DigitalData.Core.DTO` to `DigitalData.Core.Application.Interfaces` and `DigitalData.Core.Application.DTO`, improving maintainability and clarity.

Updated using directives across multiple files to reflect the new structure, ensuring functionality remains intact.

Project references in `DigitalData.Core.API.csproj` have been consolidated to include the new Application project.

Introduced new classes and interfaces such as `BaseDTO`, `CookieConsentSettings`, `DataResult`, `Notice`, and `Result` to enhance data transfer and service result handling.

Updated `IRepository`, `ICRUDRepository`, and `IEntityMapper` interfaces to facilitate CRUD operations and entity mapping.

Added extension methods in `Extensions.cs` to improve repository usability.

New interfaces for HTTP client services have been added, enhancing external API call handling.

Overall, these changes reflect a significant restructuring aimed at improving organization and preparing for future development.

DigitalData.Core.Application/DTO/DIExtensions.cs

@@ -0,0 +1,33 @@
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using System.Configuration;
+
+namespace DigitalData.Core.Application.DTO
+{
+    /// <summary>
+    /// Provides extension methods for dependency injection.
+    /// </summary>
+    public static class DIExtensions
+    {
+        /// <summary>
+        /// Adds the <see cref="CookieConsentSettings"/> to the service collection.
+        /// </summary>
+        /// <param name="services">The service collection to add the settings to.</param>
+        /// <returns>The updated service collection.</returns>
+        /// <exception cref="ConfigurationErrorsException">
+        /// Thrown if the 'CookieConsentSettings' section is missing or improperly configured in appsettings.json.
+        /// </exception>
+        public static IServiceCollection AddCookieConsentSettings(this IServiceCollection services)
+        {
+            services.AddSingleton(sp =>
+            {
+                var configuration = sp.GetRequiredService<IConfiguration>();
+                var settings = configuration.GetSection("CookieConsentSettings").Get<CookieConsentSettings>();
+                return settings is null
+                    ? throw new ConfigurationErrorsException("The 'CookieConsentSettings' section is missing or improperly configured in appsettings.json.")
+                    : settings;
+            });
+            return services;
+        }
+    }
+}