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/AppSettings.cs

@@ -8,4 +8,4 @@ public sealed class AppSettings
 
     public string ConnectionString { get; init; } = string.Empty;
     public RabbitMqSettings RabbitMq { get; init; } = null!;
-}
+}