[meta] Version 2.x

This meta issue tracks the work needed for the next major version of this module.

The goal of the new major is to address standing issue from both UX and functionality side.
A non-exhaustive list of points to address:

• remove complex code like single "child element" default value handling;
• UX improvements around fixed cardinality elements: rely on the "Add more" button instead of pre-rendering all items;
• Add a remove button per row;
• Better detection of empty rows;
• Simpler handling of default values: possibly allow to process values "to" and "from" form (like ConfigTarget does).