Related: #179

Changes include:
- Updated `AbstractOrderingStep.php` to handle null case in `getOrder` method and modified return
type.
- Refactored `Order.php` to remove unnecessary checks and improve readability.
- Ensured safety against calling non-existent `save()` method in `Checkout.php`.
- Simplified address getting logic in `CustomerData.php`.
- Removed unnecessary check in isUserB2B function.

Related: #172

Improve readability and interpretability of code by explicitly stating null in union types. This
change has been applied across multiple files and functions.

PHP8.4 compatibility

Related: quiqqer/order#163

fix: Fixed problem with missing first and last names. #138 pcsg/kunden/bow-modellhandel-template#89 pcsg/projects/walking-family-project#154

feat: CustomerData step, edit button improved.