[feature] Actions reordering in the workflow editor

As a Citizen Developer
I want to be able to reorder actions in existing workflows
So that I can more easily update existing workflows.

Technical Details:
Check https://dndkit.com/

Start at the workflow editor entry point and review the dndkit documentation linked in the issue. Trace how actions in existing workflows are rendered and persisted, then verify that users can reorder them and that the updated order remains after saving and reopening a workflow.

Written by the indexing model from the issue text.