refactor: replace local dal abstractions with hrynco-ef packages

Remove duplicate IEntity, Entity, ITransaction, IUnitOfWork, EfRepository,
EfUnitOfWork, EfTransactionAdapter — now consumed from HrynCo.DAL.Abstract
and HrynCo.DAL.EF packages (1.0.1).

Ref: IT-0

HrynCo.NotificationService.DAL.EF/Core/UnitOfWork.cs

@@ -1,3 +1,5 @@
+using HrynCo.DAL.EF.Core;
+
 namespace HrynCo.NotificationService.DAL.EF.Core;
 
 internal sealed class UnitOfWork : EfUnitOfWork<NotificationDbContext>