Fix/acl for forward (#1305)

Fix ACL on routed traffic and code refactor

client/firewall/iface.go

@@ -0,0 +1,11 @@
+package firewall
+
+import "github.com/netbirdio/netbird/iface"
+
+// IFaceMapper defines subset methods of interface required for manager
+type IFaceMapper interface {
+	Name() string
+	Address() iface.WGAddress
+	IsUserspaceBind() bool
+	SetFilter(iface.PacketFilter) error
+}