Add ZSON extension to /contrib/

When Who What
2021-07-12 18:52:51 Peter Eisentraut (petere) Closed in commitfest 2021-07 with status: Rejected
2021-06-04 15:12:43 Aleksander Alekseev (aalekseev) Changed targetversion to None
2021-06-04 15:12:28 Aleksander Alekseev (aalekseev) Changed authors to Aleksander Alekseev (aalekseev)
2021-06-04 15:12:28 Aleksander Alekseev (aalekseev) Changed targetversion to 15
2021-06-04 15:12:28 Aleksander Alekseev (aalekseev) Changed topic to Miscellaneous
2021-06-04 15:11:49 Aleksander Alekseev (aalekseev) Attached mail thread CAJ7c6TP3fCC9TNKJBQAcEf4c=L7XQZ7QvuUayLgjhNQMD_5M_A@mail.gmail.com
2021-06-04 15:11:48 Aleksander Alekseev (aalekseev) Created patch record