Refactored and fixed errors

SchengenVisaApi/ApplicationLayer/DependencyInjection.cs

@@ -0,0 +1,16 @@
+using ApplicationLayer.VisaApplications.Handlers;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace ApplicationLayer;
+
+/// Provides methods to add services to DI-container
+public static class DependencyInjection
+{
+    /// Add services for Application layer
+    public static IServiceCollection AddApplicationLayer(this IServiceCollection services)
+    {
+        services.AddScoped<IVisaApplicationsRequestHandler, VisaApplicationRequestsHandler>();
+
+        return services;
+    }
+}