Deprecated dynamic property creation in UpdateAvailabilityForm

Problem/Motivation

When navigating to the node availability path (node/{nid}/availability) after making a node type bookable and creating a node of that type, the following PHP deprecation warnings are observed:

Deprecated function: Creation of dynamic property Drupal\bee\Form\UpdateAvailabilityForm::$nodetypeStorage is deprecated in Drupal\bee\Form\UpdateAvailabilityForm->__construct() (line 45 of modules/contrib/bee/src/Form/UpdateAvailabilityForm.php).
Deprecated function: Creation of dynamic property Drupal\bee\Form\UpdateAvailabilityForm::$nodeStorage is deprecated in Drupal\bee\Form\UpdateAvailabilityForm->__construct() (line 46 of modules/contrib/bee/src/Form/UpdateAvailabilityForm.php).

This occurs because properties $nodetypeStorage and $nodeStorage are being dynamically created in the constructor of UpdateAvailabilityForm without being declared within the class definition.

See https://www.php.net/manual/en/class.allowdynamicproperties.php

Steps to reproduce

1. Install the BEE module.
2. Define a node type and set it as bookable.
3. Create a node of the bookable type.
4. Visit node/{nid}/availability.
5. Observe the deprecated warnings.

Proposed resolution

Modify the UpdateAvailabilityForm class to declare these properties explicitly at the beginning of the class.