Enable label-actions on the react-native repository (#28374)

Summary:
Enhance our issue management workflow by having the bot respond automatically whenever a label is applied to the issue.

## Changelog

[Internal] - CI
Pull Request resolved: https://github.com/facebook/react-native/pull/28374

Test Plan: Not tested. If needed, could be applied to a different, test repository.

Reviewed By: cpojer

Differential Revision: D20606887

Pulled By: hramos

fbshipit-source-id: 874d1464527ea76bf51394a7d3e98e4fd8f69345