Group dragging feature lost in 8.x-1.2

Created issue fork and fixed the patch so it applies to 2.1.x.

I did add changes to make this work with Claro theme in Drupal 10. The structure was not preserved when dragging rows around and it did cause some weird issues where relationships were lost.

I saw some changes that were done here were added by the 🐛 Not working with Group By feature RTBC . I modified the code so this will apply with the latest patch from that issue.
At the moment this will fix

• Hierarchy functionality - it is broken in the Claro theme, it needs one header class, and rendering the indentation part was not correct, it did remove the SVG and there were no visible parent-child relationship lines available
• custom entities (at the moment it expects 'nid' as entity id key, but others have 'id' usually)

I did test this and did not find any weird behavior related to moving things around. Previously it messed things up, ordering was wrong, indentation incorrect, and was lost.

Hopefully, someone can take a look at this with the other issue and see if it is possible to merge these things to a new release.

The hierarchy setting introduced in #2867348 and committed to 2.1.4 seems to have solved the problem - all that's needed is tick the Enable hierarchy box in the Draggableviews field settiings. Can be closed I guess.

Automatically closed - issue fixed for 2 weeks with no activity.