feat(firewall): use all default routes

- Accept output traffic from all default routes through VPN interface
- Accept output from all default routes to outbound subnets
- Accept all input traffic on ports for all default routes
- Add IP rules for all default routes

internal/routing/routing.go

@@ -15,7 +15,6 @@ type ReadWriter interface {
 
 type Reader interface {
 	DefaultRouteGetter
-	DefaultIPGetter
 	LocalSubnetGetter
 	LocalNetworksGetter
 	VPNGetter