- Rewrite auto-rejoin code and move it into muc module

This is a dedicated event so we dont have to use the our-show event

- Add own module for roster code
- Use avatars with status integrated
- Favor performance over features

- Add plural support for get_uf_affiliation()
- Accept nbxmpp.Role and nbxmpp.Affiliation as arguments
- Add is_affiliation_change_allowed()
- Add is_role_change_allowed()

Fixes #9835

The issue reported by concerto [1] is a regression since af312830.

[1] https://conference.gajim.org:5281/muc_log/gajim/2019-09-10#df591057-8693-4e76-bbc2-334d839c6adc

All avatars are available under ~/.cache/gajim/avatars

see: https://lazka.github.io/pgi-docs/Gdk-3.0/classes/Cursor.html#Gdk.Cursor.new_from_name

Fixes #9800

Caches now also the circle clipping