feat(internal/wireguard): opportunistic kernelspace

- Auto detect if kernelspace implementation is available
- Fallback to Go userspace implementation if kernel is not available

internal/netlink/family_test.go

@@ -0,0 +1,21 @@
+package netlink
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_NetLink_IsWireguardSupported(t *testing.T) {
+	t.Skip() // TODO unskip once the data race problem with netlink.GenlFamilyList() is fixed
+
+	t.Parallel()
+	netLink := &NetLink{}
+	ok, err := netLink.IsWireguardSupported()
+	require.NoError(t, err)
+	if ok { // cannot assert since this depends on kernel
+		t.Log("wireguard is supported")
+	} else {
+		t.Log("wireguard is not supported")
+	}
+}