net/samba420: Update 4.20

Changelog: https://wiki.samba.org/index.php/Release_Planning_for_Samba_4.20

PR: 280533
Sponsored by: Klara, Inc.
Approved by: 0mp (mentor)
Approved by: samba (0mp, kiwi)
Co-authored-by: Xavier Beaudouin <kiwi@FreeBSD.org>