`editor.pagination` dsl improvements

[alamqadem]

I report here a list of improvements required by users of the language:

• [x] add a devkit for the pagination language that includes the runtime;
  • building without including the runtime in the dependencies at the moment causes errors;
• [x] we would like to not see the pages if there is only 1 page, we would like to show only the collection of nodes;
• [x] we would like to specify the page that we want to see instead of only using next and previous;
• [ ] pressing in the find usages on a reference doesn't change the page to display the target
  • here we might need support from jetbrains for an API that allows to customise navigation to a target
• [ ] in the diff view: if a change is not on the visible page the whole node is highlighted, here we would like to find a solution, as we want to do for errors

[HeikoBecker]

Minor usability improvement: I would also appreciate if the languages and runtimes were clustered into a devkit.