Feature: #109271 - Add TCA configuration for dynamic page creation wizard steps

Description

The page creation wizard now supports a dynamic configuration for its steps via TCA. This allows to define which fields are displayed in which step of the wizard, depending on the pagetype.

A new TCA configuration option wizardSteps is introduced for the pages table. Each step is defined by a unique key and contains a title and a list of fields to be displayed.

The steps are sorted, allowing steps to be positioned relative to each other using the after or before keys.

If a page type has required fields that are not explicitly assigned to any configured wizard step, a fallback step name is automatically appended at the end.

Example

Defining wizard steps for a custom page type in TCA:

EXT:my_extension/Configuration/TCA/Overrides/pages.php

$GLOBALS['TCA']['pages']['types']['123']['wizardSteps'] = [
    'setup' => [
        'title' => 'LLL:EXT:backend/Resources/Private/Language/Wizards/page.xlf:step.setup',
        'fields' => ['title', 'slug', 'nav_title', 'hidden', 'nav_hide'],
    ],
    'special' => [
        'title' => 'LLL:EXT:my_extension/Resources/Private/Language/locallang.xlf:wizard.special_step',
        'fields' => ['my_custom_field'],
        'after' => ['setup'],
    ],
];

Impact

It is now possible to configure fields, steps (and their order) in the page creation wizard.