fix: additionalProperties defaults are not propagated to the form

[kovayur]

Reasons for making this change

fixes #2593

Checklist

• [ ] I'm updating documentation
  • [ ] I've checked the rendering of the Markdown text I've added
• [x] I'm adding or updating code
  • [x] I've added and/or updated tests. I've run npm run test:update to update snapshots, if needed.
  • [ ] I've updated docs if needed
  • [ ] I've updated the changelog with a description of the PR
• [ ] I'm adding a new feature
  • [ ] I've updated the playground with an example use of the feature

[heath-freenome]

@kovayur This is a great addition... Sorry it has taken so long for someone to look at it. I'm sad to say that the current branch has been locked down for security fixes only as we are actively working on a v5 (see the rjsf-v5 branch). One thing is that v5 is has major breaking changes, including refactoring the utils.js file into its own package @rjsf/utils which is now all typescript. If you want to replicate this change into rjsf-v5 within the @rjsf/utils package feel free to do so and I will review and approve. Do, please also include an update to the CHANGELOG.md file for this.

[heath-freenome]

Closing this PR as it is reimplemented in #3435

[kovayur]

Thanks @heath-freenome for getting this done!