feat(protonvpn): port forwarding support with NAT-PMP (#1543)

Co-authored-by: Nicholas Xavier <nicho@nicho.dev>

internal/configuration/settings/portforward.go

@@ -40,7 +40,10 @@ func (p PortForwarding) validate(vpnProvider string) (err error) {
 	if *p.Provider != "" {
 		providerSelected = *p.Provider
 	}
-	validProviders := []string{providers.PrivateInternetAccess}
+	validProviders := []string{
+		providers.PrivateInternetAccess,
+		providers.Protonvpn,
+	}
 	if err = validate.IsOneOf(providerSelected, validProviders...); err != nil {
 		return fmt.Errorf("%w: %w", ErrPortForwardingEnabled, err)
 	}

internal/configuration/settings/wireguardselection.go

@@ -16,7 +16,7 @@ type WireguardSelection struct {
 	// It is only used with VPN providers generating Wireguard
 	// configurations specific to each server and user.
 	// To indicate it should not be used, it should be set
-	// to netaddr.IPv4Unspecified(). It can never be the zero value
+	// to netip.IPv4Unspecified(). It can never be the zero value
 	// in the internal state.
 	EndpointIP netip.Addr `json:"endpoint_ip"`
 	// EndpointPort is a the server port to use for the VPN server.