Volto form block fixes

[robgietema]

• I signed and returned the Plone Contributor Agreement, and received and accepted an invitation to join a team in the Plone GitHub organization.
• I verified there aren't other open pull requests for the same change.
• I followed the guidelines in Contributing to Volto.
• I succesfully ran code linting checks on my changes locally.
• I succesfully ran unit tests on my changes locally.
• I succesfully ran acceptance tests on my changes locally.
• If needed, I added new tests for my changes.
• If needed, I added documentation for my changes, either in the Storybook or narrative documentation.
• I included a change log entry in my commits.

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Closes #

[netlify]

✅ Deploy Preview for plone-components canceled.

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[davisagli]

Please add release notes and fix the lint errors and failing unit tests.

[stevepiercy]

This PR should also render its Storybook. We recently merged a PR that should fix the pull request preview build on Netlify:
#6410

The Netlify build currently fails to recognize changes in the most recent commit:
https://app.netlify.com/sites/plone-components/deploys/670fb4bff3f6740008e0d09f

[stevepiercy]

I reviewed only the .pot and news, both of which look good, with a couple of MyST markup enhancements and a question.

Will this PR need developer documentation? For example:

• https://6.docs.plone.org/volto/development/widget.html

[robgietema]

I reviewed only the .pot and news, both of which look good, with a couple of MyST markup enhancements and a question.

Will this PR need developer documentation? For example:

• https://6.docs.plone.org/volto/development/widget.html

The issues are fixed. The page for those widgets is about declaring widgets in the backend not the frontend so doesn't make sense to add anything on that page.

[robgietema]

Please add release notes and fix the lint errors and failing unit tests.

Done