[widgets][dataformateditor] Refactor to allow folding of content

The editor can get pretty long pretty quickly if many
fields are added. Especially array entries or object
entries. Making their repsective editors foldable
allows the user to more easily go through the content
of the editor.
6 jobs for 236_add_folding_to_dataformat_editors in 56 minutes (queued for 4 seconds)
Status Name Job ID Coverage
  Build
passed build_linux_36 #201353
docker

00:10:02

90.0%
passed build_linux_37 #201354
docker

00:09:39

90.0%
passed build_macosx_36 #201287
macosx

00:43:20

90.0%
passed build_macosx_37 #201288
macosx

00:42:52

90.0%
failed build_linux_36 #201289
docker

failed build_linux_37 #201290
docker