feat: Presence identity module to support other auth mechanisms.

resources/prosody-plugins/mod_presence_identity.lua

 -- for that session.
 function on_message(event)
     if event and event["stanza"] then
-      if event.origin and event.origin.jitsi_meet_context_user then
+      if event.origin then
+          local user;
+          local group;
+          if event.origin.jitsi_meet_context_user then
+              user = event.origin.jitsi_meet_context_user;
+              group = event.origin.jitsi_meet_context_group;
+          else
+              user = { id = event.origin.username }; -- when using auth similar to internal_hashed
+          end
 
           update_presence_identity(
               event.stanza,
-              event.origin.jitsi_meet_context_user,
-              event.origin.jitsi_meet_context_group
+              user,
+              group
           );
-
       end
     end
 end