Refactor Customer and User Repository Methods for ObjectID Handling

- Updated GetByIDs methods in customer and user repositories to convert string IDs to bson.ObjectID, ensuring proper handling of MongoDB object IDs.
- Enhanced error handling for ID conversion to provide clearer feedback when invalid IDs are provided.
- Modified notification service calls in customer and user services to use context.Background() for asynchronous email sending, improving concurrency management.
- Ensured consistent handling of company IDs in the customer repository for retrieving customers by companies.

internal/notification/service.go

@@ -397,6 +397,10 @@ func (s *notificationService) getCustomers(ctx context.Context, values []string,
 	recipients := make([]notificationRecipient, 0)
 
 	if target == string(TargetAudienceSpecificRole) {
+		if len(values) == 0 {
+			return nil, errors.New("no role provided")
+		}
+
 		customers, err := s.customerService.GetCustomersByRole(ctx, values[0])
 		if err != nil {
 			return nil, err