[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 Job ID Name Coverage
  Build
passed #201353
docker
build_linux_36

00:10:02

90.0%
passed #201354
docker
build_linux_37

00:09:39

90.0%
passed #201287
macosx
build_macosx_36

00:43:20

90.0%
passed #201288
macosx
build_macosx_37

00:42:52

90.0%
failed #201289
docker
build_linux_36

failed #201290
docker
build_linux_37