Fix guests joining a call
Fix guests joining a call

Guests dont load the participants tab, so they failed on
finding themselves in the participant list to update the call flags.
Now they add themselves on loading the conversation.

Signed-off-by: Joas Schilling <ab43a7c9cb5b2380afc4ddf8b3e2583169b39a02@schilljs.com>

nextcloud/spreed,nextcloud/spreed,nextcloud/spreed