Implement XEP-0215 External Service Discovery

Description

Even though https://xmpp.org/extensions/xep-0215.html is deferred, it's useful to have, for instance when working with Jitsi Meet.

Environment

None
Fixed

Assignee

Dave Cridland

Reporter

Guus der Kinderen

Labels

None

Expected Effort

None

Ignite Forum URL

None

Fix versions

Priority

Minor
Configure