Enhance Customer model to include role attribute and update related components

- Added a new `role` attribute to the `Customer` model in `customer.dart` and updated the corresponding generated files.
- Modified the `AuthViewModel` to set the user role based on the logged-in user's role.
- Updated UI components in `TenderDetailActions` and `DesktopTendersPage` to conditionally render elements based on the user's role.
- Refactored tests to validate the new role attribute in the `Customer` model.

lib/data/services/model/customer/customer.dart

@@ -33,6 +33,7 @@ abstract class Customer with _$Customer {
     required String? language,
     required String? username,
     required String? currency,
+    required String? role,
     required String? timezone,
     @JsonKey(name: 'created_at') required int? createdAt,
     @JsonKey(name: 'updated_at') required int? updatedAt,