Pass MessageProperties through add_message to the UI so that plugins can use it
Right now, the raw MessageProperties is passed in to the message received event, but then in ChatControl they are not passed along to add_message or into the ConversationView or MessageRow at all, so plugins hooking into the view cannot access this data.
Context: I would like to write a plugin to add an indicator to message that have a thread to show what thread they are in, but currently properties.thread is not passed in to the UI and so I don't have access to it there.