Export structure to paragraph sets YAML

Moving this to the active development version.

Hi, consider this module https://www.drupal.org/project/paragraphs_sets_plugins_ui → it has a working solution for a ui and yaml export

It is developed by me, I do not mind including it as a submodule to this one if this makes sense

Let me know if any adjustments should be done there

I will prepare a MR with a submodule

I don't think this needs to be a submodule. I'm totally fine with it being a separate module :)