Fix/acl for forward (#1305)

Fix ACL on routed traffic and code refactor

client/firewall/create.go

@@ -0,0 +1,32 @@
+//go:build !linux || android
+
+package firewall
+
+import (
+	"context"
+	"fmt"
+	"runtime"
+
+	log "github.com/sirupsen/logrus"
+
+	firewall "github.com/netbirdio/netbird/client/firewall/manager"
+	"github.com/netbirdio/netbird/client/firewall/uspfilter"
+)
+
+// NewFirewall creates a firewall manager instance
+func NewFirewall(context context.Context, iface IFaceMapper) (firewall.Manager, error) {
+	if !iface.IsUserspaceBind() {
+		return nil, fmt.Errorf("not implemented for this OS: %s", runtime.GOOS)
+	}
+
+	// use userspace packet filtering firewall
+	fm, err := uspfilter.Create(iface)
+	if err != nil {
+		return nil, err
+	}
+	err = fm.AllowNetbird()
+	if err != nil {
+		log.Warnf("failed to allow netbird interface traffic: %v", err)
+	}
+	return fm, nil
+}