[PROVISIONING] UI notification: introduce send_signal function

Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>
[PROVISIONING] UI notification: introduce dbus signal support

Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>
[PROVISIONING] UI notification: implement dbus signal support

Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>
[PROVISIONING] UI notification: implement send_signal function

Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>
[PROVISIONING] UI notification: call send_signal function

Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>
[PROVISIONING] UI notification: fix test script to handle notification

Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>