refactor: replace internal UnitOfWork with NotificationUnitOfWork and NotificationBaseRepository

- Consolidate unit of work implementation with NotificationUnitOfWork.
- Refactor repositories to use NotificationBaseRepository for consistency.
- Simplify request handlers by removing IUnitOfWork dependency.
- Update related tests and service registration.

HrynCo.NotificationService.Services/EmailTemplates/Create/CreateEmailTemplateHandler.cs

@@ -1,4 +1,3 @@
-using HrynCo.DAL.Abstract;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.DAL.Abstract.Templates;
 using HrynCo.NotificationService.Services.Core;
@@ -14,9 +13,8 @@ internal sealed class CreateEmailTemplateHandler
 
     public CreateEmailTemplateHandler(
         IContextualSerilogLogger<CreateEmailTemplateCommand> logger,
-        IUnitOfWork unitOfWork,
         IEmailTemplateRepository templates)
-        : base(logger, unitOfWork)
+        : base(logger)
     {
         _templates = templates;
     }