:sparkles: [#4707] Resizable json widget

[robinmolen]

Closes #4707

Changes

• Adds the option to resize the json widget manually, via a new isResizable property
• Made the Action Variable json widget resizable

Checklist

Check off the items that are completed or not relevant.

• Impact on features

  • [X] Checked copying a form
  • [X] Checked import/export of a form
  • [X] Config checks in the configuration overview admin page
  • [X] Problem detection in the admin email digest is handled

• Release management

  • [X] I have labelled the PR as "needs-backport" accordingly

• I have updated the translations assets (you do NOT need to provide translations)

  • [X] Ran ./bin/makemessages_js.sh
  • [X] Ran ./bin/compilemessages_js.sh

• Commit hygiene

  • [X] Commit messages refer to the relevant Github issue
  • [X] Commit messages explain the "why" of change, not the how

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.55%. Comparing base (7a6e0d3) to head (2d3356a). Report is 8 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #4786 +/- ## ======================================= Coverage 96.55% 96.55% ======================================= Files 748 748 Lines 25413 25413 Branches 3358 3358 ======================================= Hits 24538 24538 Misses 610 610 Partials 265 265 ```

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[robinmolen]

I've made a couple of changes..

All Json widget's are now resizable, starting from the default width. At first I only made the "set a form variable action" json widget resizable, because the ticket was regarding that situation. But there isn't a real reason why only that json widget should be resizable, so the functionality is now available for all json widgets.

The json widget is now resizable both horizontal and vertical, and the error message issue has been resolved