Private / Nat peers with persistence but no endpoint

[defect-track]

Hello,

have the use case where some of my peers are behind a Firewall where it isn't possible to get an inbound port opened for security reasons. However, if you just configure the persistence for these clients like described in https://www.wireguard.com/quickstart/#nat-and-firewall-traversal-persistence they can be still part of your VPN.
Reading through the code you can set the persistence but only if an endpoint is defined which will of course fail in this scenario. Believe that this is quite a common use case?

My suggestion would be to introduce a new variable like "wireguard_private_peers" where you can define a list of peers located behind a firewall which will trigger to not populate the "Endpoint".