Add DNS server in servizi.linux.it to test an automation workflow for Sandstorm's certificate renewal

Unfortunately, Sandstorms (https://servizi.linux.it) requires a special "wildcard certificate" covering all sub-domains. So, Let's Encrypt requires a special extra verification step: before every renewal we also need to deploy a new TXT token in our DNS zone.

Current Workaround and Full Context

https://gitpull.it/T96

TL;DR at the moment @valerio.bozzolan invests 5 minutes every 2 months to manually update this token.

Proposed Solution

• evaluate "modern" Free Software DNS servers with nice APIs compatible with servizi.linux.it: answer, just BIND9 is compatible. lol
• write a stupid script that takes a token and puts that in BIND9 (done - see https://gitpull.it/T96 )
• install BIND9 in server servizi.linux.it (https://gitlab.com/ItalianLinuxSociety/ils-infrastructure/-/blob/main/INVENTORY.md#servers-inventory) - people who can do this: gnu, mte90, oirasor
• understand how to create a renewal hook with Let's Encrypt

Hours invested

LOL at some point there is a point of no return.

• Valerio: 5 minutes every 90 days
  • 2020: ~1 hour
  • 2021: ~40 minutes
  • 2022: ~20 minutes
  • 2024: ~20 minutes