Make all soup_session calls async in `gtr-dl-teams`
We've three calls to the soup_session_send_message in the gtr-dl-teams:
- https://gitlab.gnome.org/GNOME/gtranslator/-/blob/master/src/gtr-dl-teams.c#L464
- https://gitlab.gnome.org/GNOME/gtranslator/-/blob/master/src/gtr-dl-teams.c#L196
- https://gitlab.gnome.org/GNOME/gtranslator/-/blob/master/src/gtr-dl-teams.c#L378
These calls are synchronous so it locks the UI and with a bad connection this could be a problem. We should replace that calls to use the async method soup_session_send_async: https://developer.gnome.org/libsoup/stable/libsoup-client-howto.html#id-1.2.3.6.9