Consolidate scripts into k8s-traditional hack dir.

hack/check-go-mod.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+# Copyright 2019 The Kubernetes Authors.
+# SPDX-License-Identifier: Apache-2.0
+
+set -x
+set -e
+
+# verify all modules pass validation
+for i in $(find . -name go.mod); do
+  pushd .
+  cd $(dirname $i);
+  go list -m -json all > /dev/null
+  go mod tidy -v
+  popd
+done
+
+# Need better check.  This is repeated git diff check
+# more pain than benefit for most people 25Apr2020
+## verify no changes to go.mods -- these should be part of the PR
+# find . -name go.sum | xargs git checkout --
+# git add .
+# git diff-index HEAD --exit-code