Open 1:1 chat instead of private message when doubleclicking a participant in a non-anonymous group chat
Doubleclicking a participant in a non-anonymous group chat should open a 1:1 chat (instead of a private message).
Fixes #9422 and adds a setting in Preferences > Chat.
To quote docs.modernxmpp.org:
If real JIDs are known to all participants, it is preferable to use that for private communication to avoid confusion. Through-MUC PMs have the following disadvantages:
- Only work while connected to the group chat
- Do not interact well with multiple devices (e.g. not all of a recipient's devices may be in a group chat)
- Can cause confusion if talking to the same person through different views (e.g. if the person is already a contact in your roster, and you already have a chat open with them)
Additionally avoids weird behaviour like:
- Private Message sent through group chat to self
- OMEMO through Private Messages (Fixes gajim-plugins#307)