Add site-to-site support
Counterpart of turris/foris-controller/foris-controller-openvpn_client-module#8
There might two checkboxes: "Enable site-to-site". If enabled, the second one "Masquraded" would become active.
Enabling the first checkbox would basically add VPN interface.
Depending on the state of the second checkbox we would either:
- add the interface to LAN zone (disabled)
- add the interface to LAN (or WAN??) zone and masquerade all traffic passing through it.