cli: Introduce `write_labeled!` template formatter macro

[Veykril]

Mainly an experiment to see if this looks more readable / uniform.

Checklist

If applicable:

• [ ] I have updated CHANGELOG.md
• [ ] I have updated the documentation (README.md, docs/, demos/)
• [ ] I have updated the config schema (cli/src/config-schema.json)
• [ ] I have added tests to cover my changes

[PhilipMetzger]

I personally don't like the macro variant, as it doesn't improve the readability of the code.

[Veykril]

Fair, I am indifferent to the change so mainly opened it to see opinions.