Update the user validation method in both `onUserSaveBegin` and `onUserSaveEnd` events. The
previous validation was using `QUI::getUsers()->isUser($User)`, which was replaced with a check for
`$User` instance of `QUI\\Users\\User` for improved reliability.

- Updated PHPStan version from 1.11.8 to 1.12.13 in phars.xml
- Changed User class interfaces in the event handlers from QUI\Users\User to
QUI\Interfaces\Users\User
- Also, added additional checks and updated function parameters for type consistency.

Improve user verification in ajax backend passwordMail by adding an instance check for
QUI\\Users\\User before calling sendPassword method.
Remove redundant error messages in phpstan-baseline.neon associated with previously incorrect user
activation logic and unsupported comparison evaluations in Customers.php and Search.php.
Correct arguments for activate method in Customers.php from false to empty string.
Add 'users.customerId' to allowed search columns and adjust type hints for arguments in `limit` and
`setFilter` methods in Search.php to include spaces for better readability.

Related: #67

1. Simplified condition checks for 'firstname' and 'lastname' using the 'empty()' function.
2. Refactored the type hinting of parameters for the 'addUserToCustomerGroup',
'removeUserFromCustomerGroup', and 'setAttributesToCustomer' methods.
3. Updated the type hinting for the 'getEntityTypeTitle' method, adding a possibility to receive
null.

Related: #67

This commit includes enhancements in customer creation feature. Specifically, it modifies the
`createCustomer` function by adding a new parameter `$attributes` to handle attribute data during
customer creation process. Moreover, it introduces UI components to collect these attribute
details. Updates have been made to the associated form elements, button actions and display methods
to accommodate these changes. In addition, it makes considerable changes in the backend JavaScript
files to facilitate frontend changes and to meet compatibility.

There's also a change in error handling part where it replaces the `try-catch` block, which attempt
to get the standard address, with direct command. This assures the retrieval of the standard
address, if exists, else a new address will be created implicitly.

Finally, few general code improvements are done like changing usage of `var` to `const` or `let`
where necessary for better maintainability. A minor adjustment on window height property is also
made in `CustomerWindow.js` file.

Related: #68

Automatic customer number assignment when ordering

Add QUIQQER Tooling

See merge request !36

fix: open items list has UUID of the user in the file name

See merge request !52

related: pcsg/buero#443

Next 2.x

Closes pcsg/buero#439

See merge request !51

fix: customer select control - 0 user

See merge request !49

related: pcsg/buero#415

related: pcsg/buero#415

fix: customer selection control Double-click behaviour

See merge request !48

related: pcsg/buero#415

related: pcsg/buero#415

The behaviour of the customer window has been completely revised.
An attempt has been made not to produce such constant flickering.

related: pcsg/buero#415

fix: post incoming payments

See merge request !47

related: pcsg/buero#421

fix: file attachments cannot be downloaded via hash

See merge request !46

related: pcsg/buero#419

fix: customer user extra fields migration

See merge request !45