Add a CI workflow to sync repository-wide labels

[per1234]

The workflow will configure the labels of this repository according to the universal labels defined by https://github.com/107-systems/.github/blob/main/universal-repository-labels.json combined with any repository-specific labels defined in a JSON file located in the .github/repository-labels-data folder.

Fixes #23

[per1234]

If you have any labels specific to this repository, I'm happy to add the JSON file for those as well.

A warning: when this is merged, it will remove the stock GitHub labels from the repository, which will also result in them being removed from the PRs and issues that have them.

[aentinger]

Terrific, can't wait to see this in action 🚀

[aentinger]

Fair warning, if I get around I'll reset the now missing labels, but somehow I don't think it's so very imporant.

[per1234]

Terrific, can't wait to see this in action

Same here! This is something I've been wanting to do for a long time, but never got the motivation to make it happen until now. That initial PoC I posted my notes about in #23 was done 1.5 years ago!

My crazy dream is that the same could be done in Arduino's repositories. Automating the migration from the deprecated labels to the standardized ones would be a very nice thing to add for applying this to repos that have a large base of issues/PRs with deprecated labels.