Improve the Mac menu bar icon, hardly visible if connected or not

[b-johannes]

Please change the icon on the menu bar. It is very hard to see if it is connected. Please follow the Apple UI guidelines: here for example the volume button is light grey if volume is deactivated and solid white when connected. Wireguard VPN Client does the same, as many other software, too.

Connected

Not connected

As reference Volume muted

Volume on

[jwijenbergh]

This is the Linux client not the apple client, for that see https://github.com/eduvpn/apple