[self reminder]: update status when connecting in Monitor mode

[facontidavide]

Colors not updated when message number == 0.

[esromneb]

This is a theory: In SidepanelMonitor::on_timer() the "header" updates don't contribute to the updates, only the "transitions" do. This is because the "transition" loop has this https://github.com/BehaviorTree/Groot/blob/dd61e4b1a5cd97a014f5e01b1482cfb1c7d75c89/bt_editor/sidepanel_monitor.cpp#L90 but the loop above (starting on line 68) has no similar push_back. Is this correct?