Create template for WireGuard VPNCONN

Create template for WireGuard VPNCONN

WireGuard VPN connections have so many different cnfvars when compared
to IPSec vpns, that we create a different template for them. The
"vpnconn" function uses the VPNCONN_PROTO to decide which of the two
templates it should use.

Also add two fully functional wireguard vpnconns to test config
(a roadwarrior and a site-to-site) including interface, own keys and
foreign keys.

This is the first step in cleaning up vpn connection creation in QA.
The new functionality is not used there, yet, but can be easily be
triggered in the future to simplify vpnconn creation.