lint(errorlint): handle wrapped errors

Enable errorlint and preserve wrapped error chains so runtime checks
and tests classify failures correctly. This also makes Route53
surface insert failures instead of silently dropping them.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

plugin/kubernetes/xfr_test.go

@@ -1,6 +1,7 @@
 package kubernetes
 
 import (
+	"errors"
 	"net"
 	"strings"
 	"testing"
@@ -20,7 +21,7 @@ func TestKubernetesTransferNonAuthZone(t *testing.T) {
 	dnsmsg.SetAxfr("example.com")
 
 	_, err := k.Transfer("example.com", 0)
-	if err != transfer.ErrNotAuthoritative {
+	if !errors.Is(err, transfer.ErrNotAuthoritative) {
 		t.Error(err)
 	}
 }