VPN connected instance indicators and fixing OpenVPN server logic

[Snuffy2]

• For Wireguard Servers, adds Connected Clients sensor
• For Wireguard Clients, adds Connected Servers sensor
• For OpenVPN Servers, adds Connected Clients sensor
• Fix OpenVPN server statistics

Fixes #285
#290

ToDo in a different PR:

• Can the connected OpenVPN clients be somehow linked to the actual clients?
  • Related, can we show when a client is connected or not

[Snuffy2]

Gonna put this out as a beta and then see if there's anything we can do regarding OpenVPN Client sensors. Will do that in a separate PR if we come up with anything.