Feature: #47006 - Extend the widget identifier with custom string

See forge#47006

Description

The parameter customWidgetId has been introduced for fluid widgets. This string is used in the widget identifier in addition to the nextWidgetNumber.

The widget identifier is used to create the GET parameter names.

A good value for the customWidgetId is the {contentObjectData.uid} to ensure no collisions happen.

Example:

<f:widget.paginate customWidgetId="{contentObjectData.uid}" ...></f:widget.paginate>

Impact

Allows to use the same fluid widget more than once on one page in different content elements.