Add theme function for form labels in JavaScript

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This would still be nice. It would also need to be added to tableselect.js so the checkbox there also has a label for accessibility. https://git.drupalcode.org/project/drupal/-/blob/11.x/core/misc/tablesel...

I have attached a patch for 11.x, please review

The Needs Review Queue Bot → tested this issue. It fails the Drupal core commit checks. Therefore, this issue status is now "Needs work".

This does not mean that the patch needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

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I rerolled it, please review.

New feature will need test coverage. Tagging for that.