Topic metadata updates

[rtibbles]

Summary

Description of the change(s) you made

• Don't make intervening folders inherit inherited properties
• Still pass down the properties to descendant resources
• Adds language as an inherited property

Reviewer guidance

How can a reviewer test these changes?

Add inherited metadata labels and language to a folder - see that on publish in Kolibri, it gets set on descendant resources, but not on the intervening folders.

References

Follow up from QA #3578 (comment)

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Contributor's Checklist

Testing:

• Critical and brittle code paths are covered by unit tests

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Reviewer's Checklist

This section is for reviewers to fill out.

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[bjester]

LGTM!