implement ConnectivityEvent
related to tpo/applications/vpn#97 (closed)
This MR adds a new ConnectivityEvent, which indicates internet connectivity changes.
Also the initialization of the ConnectivityHandler has been improved. It now returns immediately the current connection state during the registration of the connection state change listener.
In order to add a new "no-internet-state" to the tor-vpn UI, this MR reuses the already implemented ConnectivityHandler which used to signal only to the onionmasq rust core connectivity changes. It has been extended now so that it also sends an event the UI can consume.
Edited by cyberta