Format symbols for year, month, day in DateComponents#toString()
Issue related to the following post: https://forum.orekit.org/t/vote-releasing-orekit-11-0-from-release-candidate-2/1356/10?u=bcazabonne
Issue related to the following post: https://forum.orekit.org/t/vote-releasing-orekit-11-0-from-release-candidate-2/1356/10?u=bcazabonne