Recommendation is to avoid using the year nomenclature as this information is already encoded in the git repo. Avoids needing to repeatly update. Also updates AUTHORS.txt from current repo with contributor names
The extern just gets annoying to try to export the func later. We also yeet TO_UTF8 to string_utils.h for parity.
Fixes https://gitlab.com/kicad/code/kicad/issues/8576