Initial constants integration.

[rtibbles]

Summary

• Integrates standard JS constants for new metadata labels

References

Integration of JS package from this PR:
learningequality/le-utils#92

Reviewer guidance

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Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
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Reviewer checklist

• Automated test coverage is satisfactory
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• Documentation is updated
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[marcellamaki]

This looks good and like it should handle the constants changes well in the front end

[indirectlylit]

we appear to have two versions possibly because of an out-of-date kolibri-core-for-export (kolibri/core/package.json)