fix(slate): fix multiple SlateEditor editing the same field in a form

[razvanMiu]

closes #5790

[netlify]

✅ Deploy Preview for plone-components canceled.

Name	Link
🔨 Latest commit	7eb236b
🔍 Latest deploy log	https://app.netlify.com/sites/plone-components/deploys/6602d48f50b4cf0007d3cfc0

[netlify]

✅ Deploy Preview for volto canceled.

Name	Link
🔨 Latest commit	7eb236b
🔍 Latest deploy log	https://app.netlify.com/sites/volto/deploys/6602d48fd66a0a0008ddc291

[razvanMiu]

@sneridagh Looks like this pr fails because of a less file import in unit tests. It seams that the less file is not mocked so probably there is a configuration issue for jest?

FAIL __tests__/volto-slate/deserialize.test.js
  ● Test suite failed to run

    /home/runner/work/volto/volto/packages/volto-slate/src/editor/less/editor.less:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){@import 'globals.less';
                                                                                             ^

    SyntaxError: Invalid or unexpected token

      23 | import isHotkey from 'is-hotkey';
      24 |
    > 25 | import '@plone/volto-slate/editor/less/editor.less';
         | ^
      26 |
      27 | import Toolbar from '@plone/volto-slate/editor/ui/Toolbar';
      28 |

      at Runtime.createScriptFromCode (../../node_modules/.pnpm/jest-runtime@26.6.3/node_modules/jest-runtime/build/index.js:1350:14)
      at Object.<anonymous> (../volto-slate/src/editor/SlateEditor.jsx:25:1)
      at Object.<anonymous> (../volto-slate/src/editor/index.js:3:1)
      at Object.<anonymous> (../volto-slate/src/index.js:3:1)
      at Object.<anonymous> (__tests__/volto-slate/deserialize.test.js:7:1)

[sneridagh]

@razvanMiu Why did you change the import to be absolute? We should not do this unless it's a shadow-able module.
The rest LGTM.

@tiberiuichim @ichim-david Can I have a review from you too, please?