The two new options make it possible to create the interface in one namespace
and move it to a different one, as explained at https://www.wireguard.com/netns/.
Ideally, private keys never leave the host they're generated on - like
SSH. Setting generatePrivateKeyFile to true causes the PK to be
generate automatically.
After working on the last wireguard bump (#57534), we figured that it's
probably a good idea to have a basic test which confirms that a simple
VPN with wireguard still works.
This test starts two peers with a `wg0` network interface and adds a v4
and a v6 route that goes through `wg0`.
