Feature: #89509 - Data Processor to resolve FlexForm data

Description

TYPO3 offers "FlexForms", which can be used to store data within an XML structure inside a single DB column. Since this information could also be relevant in the view, a new data processor \TYPO3\CMS\Frontend\DataProcessing\FlexFormProcessor is added. It converts the FlexForm data of a given field into a Fluid readable array.

Options

`fieldName`: Field name of the column the FlexForm data is stored in (default: pi_flexform).
`as`: The variable to be used within the result (default: flexFormData).

Example of a minimal TypoScript configuration

10 = TYPO3\CMS\Frontend\DataProcessing\FlexFormProcessor

The converted array can be accessed within the Fluid template with the {flexFormData} variable.

Example of an advanced TypoScript configuration

10 = TYPO3\CMS\Frontend\DataProcessing\FlexFormProcessor
10 {
    fieldName = my_flexform_field
    as = myOutputVariable
}

The converted array can be accessed within the Fluid template with the {myOutputVariable} variable.

Example with a custom sub processor

10 = TYPO3\CMS\Frontend\DataProcessing\FlexFormProcessor
10 {
    fieldName = my_flexform_field
    as = myOutputVariable
    dataProcessing {
       10 = Vendor\MyExtension\DataProcessing\CustomFlexFormProcessor
    }
}

Impact

It's now possible to access the FlexForm data of a field in a readable way in the Fluid template.