Refactor MUCData

- Make jid property a JID
- Add occupant_jid property
- nbxmpp: Use new muc_jid attribute
3 jobs for master in 3 minutes and 2 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #12258
run-appdata

00:00:06

passed #12257
run-tests

00:02:44

 
  Build
passed #12259
run-build

00:00:11