fix: inherit EF entities from Entity base class

- TemplateEntity, ProviderEntity, ProviderUsageEntity now inherit Entity (from DAL.Abstract)
- Removes duplicated Id, Created, Updated properties from each entity

Ref: IT-628

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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

@@ -12,12 +12,18 @@ internal sealed class EfTransactionAdapter : ITransaction
         _transaction = transaction;
     }
 
-    public Task CommitAsync(CancellationToken cancellationToken = default) =>
-        _transaction.CommitAsync(cancellationToken);
+    public Task CommitAsync(CancellationToken cancellationToken = default)
+    {
+        return _transaction.CommitAsync(cancellationToken);
+    }
 
-    public Task RollbackAsync(CancellationToken cancellationToken = default) =>
-        _transaction.RollbackAsync(cancellationToken);
+    public Task RollbackAsync(CancellationToken cancellationToken = default)
+    {
+        return _transaction.RollbackAsync(cancellationToken);
+    }
 
-    public ValueTask DisposeAsync() =>
-        _transaction.DisposeAsync();
-}
+    public ValueTask DisposeAsync()
+    {
+        return _transaction.DisposeAsync();
+    }
+}