ui: add more trace points for VNC client/server messages

This adds trace points for desktop size and audio related messages.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210311182957.486939-2-berrange@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>