Add logic layer for the ACL firewall rules management.

client/internal/firewall_linux.go

@@ -0,0 +1,17 @@
+package internal
+
+import (
+	"fmt"
+
+	"github.com/netbirdio/netbird/client/firewall"
+	"github.com/netbirdio/netbird/client/firewall/iptables"
+)
+
+func buildFirewallManager() (fw firewall.Manager, err error) {
+	fw, err = iptables.Create()
+	if err != nil {
+		// TODO: handle init nftables manager when it will be implemented
+		return nil, fmt.Errorf("create iptables manager: %w", err)
+	}
+	return fw, nil
+}