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

Description

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

A new TCA configuration option wizardSteps is introduced. It currently works only 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 them 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 a configured wizard step, a fallback step is automatically appended at the end.

Example

Defining wizard steps for a custom doktype in TCA:

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

$GLOBALS['TCA']['pages']['types']['123']['wizardSteps'] = [
    'setup' => [
        'title' => 'LLL:backend.wizards.page:step.setup',
        'fields' => ['title', 'slug', 'nav_title', 'hidden', 'nav_hide'],
    ],
    'special' => [
        'title' => 'LLL:my_extension.messages: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.