Feature: #104789 - Support for contentArgumentName in AbstractViewHelper 

Description 

ContentArgumentName has been a feature on Fluid ViewHelpers for some time now. It allows ViewHelpers to link a ViewHelper argument to the children of the ViewHelper name. As a result, an input value can either be specified as an argument or as the ViewHelper's children, leading to the same result.

Example:

<!-- Tag syntax -->
<f:format.json value="{data}" />
<f:format.json>{data}</f:format.json>

<!-- Inline syntax -->
{f:format.json(value: data)}
{data -> f:format.json()}

Previously, this feature was only available to ViewHelpers using the trait \CompileWithContentArgumentAndRenderStatic . It is now available to all ViewHelpers since it has been integrated into the \AbstractViewHelper . The trait is no longer necessary.

To use the new feature, all the ViewHelper implementation needs to do is to define a method getContentArgumentName() which returns the name of the argument to be linked to the ViewHelper's children:

Example:

public function getContentArgumentName(): string
{
    return 'value';
}

Impact 

ViewHelpers using the trait \CompileWithContentArgumentAndRenderStatic should be migrated to the new feature.

\CompileWithContentArgumentAndRenderStatic will continue to work in Fluid v4, but will log a deprecation level error message. It will be removed in Fluid v5.