refactor: modularize email processing logic and improve service structure

- Extract email template handling, rendering, and sending code into `Worker.Services` project.
- Introduce `EmailTemplateService`, `EmailTemplateRenderingService`, and `SendEmailService`.
- Simplify consumer logic by delegating to scoped services.
- Update project dependencies and package references accordingly.

HrynCo.NotificationService.Worker.Services/ServiceCollectionExtensions.cs

@@ -0,0 +1,17 @@
+using HrynCo.NotificationService.Worker.Services.EmailProcessing;
+using Hrynco.RabbitMq;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace HrynCo.NotificationService.Worker.Services;
+
+public static class ServiceCollectionExtensions
+{
+    public static IServiceCollection AddNotificationWorkerServices(this IServiceCollection services)
+    {
+        services.AddSingleton<IRabbitMqPublisher, RabbitMqPublisher>();
+        services.AddScoped<IEmailTemplateService, EmailTemplateService>();
+        services.AddScoped<IEmailTemplateRenderingService, EmailTemplateRenderingService>();
+        services.AddScoped<ISendEmailService, SendEmailService>();
+        return services;
+    }
+}