Update Apollon to 2.12.9

Merge Apollon 2.12.9 to this repo (currently on 2.12.4). Changes are mostly visual (alignment of elements to grid, etc.) and probably won't have any breaking issues.

Full changelog since v2.12.4 (website might be laggy): https://github.com/ls1intum/Apollon/compare/v2.12.4...v2.12.9