fix: pass experimental_customMergeAllOf through all resolution paths

[augustynzentner]

Reasons for making this change

experimental_customeMergeAllOf was not properly passed down the resolution stack and certain scenarios didn't work well when retrieving schema.

Checklist

• I'm updating documentation
  • I've checked the rendering of the Markdown text I've added
• I'm adding or updating code
  • I've added and/or updated tests. I've run npx nx run-many --target=build --exclude=@rjsf/docs && 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]

@augustynzentner Thanks for catching and fixing this. Will you rebase to the latest and update the CHANGELOG.md file. Thanks

[heath-freenome]

I'll update the CHANGELOG.md in my PR that I have just pushed