Vendor nftables library, add utils.SupportsIPTables and utils.SupportsNFTables

Signed-off-by: Dan Winship <danwinship@redhat.com>

vendor/sigs.k8s.io/knftables/Makefile

@@ -0,0 +1,32 @@
+# Copyright 2023 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+all build:
+	echo "Usage:"
+	echo "make test   - run unit tests"
+	echo "make update - run gofmt, etc"
+	echo "make verify - run golangci, etc"
+
+clean:
+
+test:
+	./hack/test.sh
+
+update:
+	./hack/update.sh
+
+verify:
+	./hack/verify.sh
+
+.PHONY: all build clean test update verify