Remove kubectl's dependence on schema file in pkg/api/validation.

**What this PR does / why we need it**:

Makes functions in validation/schema.go private to kubectl,
further isolating kubectl.

**Which issue this PR fixes**

Part of a series of PRs to address kubernetes/community#598

**Release note**:
```release-note
NONE
```

hack/make-rules/BUILD

@@ -0,0 +1,121 @@
+# Scripts runnable from make, e.g.
+#
+#    cd $GOPATH/src/k8s.io/kubernetes
+#    make test-e2e-node
+#
+# The sh_binary rules below exist only to validate
+# dependencies; if a shell dependency is accidentally
+# deleted, a presubmit BUILD will fail.
+#
+# If the scripts sourced their dependencies from
+# $RUNFILES (rather than $BASH_SOURCE/../.. or
+# whatever), then bazel build hack/...  would install
+# runnable, hermetically sealed shell "binaries".
+# E.g. the following command would work:
+#
+#   ./bazel-bin/hack/make-rules/test-e2e-node
+#
+# TODO(#47064): Should be a sh_test instead of sh_binary
+sh_binary(
+    name = "test-cmd",
+    srcs = ["test-cmd.sh"],
+    deps = [
+        ":test-cmd-util",
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "test-e2e-node",
+    srcs = ["test-e2e-node.sh"],
+    deps = [
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "test-federation-cmd",
+    srcs = ["test-federation-cmd.sh"],
+    deps = [
+        ":test-cmd-util",
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "test-integration",
+    srcs = ["test-cmd.sh"],
+    deps = [
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "test-kubeadm-cmd",
+    srcs = ["test-kubeadm-cmd.sh"],
+    deps = [
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "build",
+    srcs = ["build.sh"],
+    deps = [
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "cross",
+    srcs = ["cross.sh"],
+    deps = [
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "test",
+    srcs = ["test.sh"],
+    deps = [
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "vet",
+    srcs = ["vet.sh"],
+    deps = [
+        "//hack/lib",
+    ],
+)
+
+sh_binary(
+    name = "verify",
+    srcs = ["verify.sh"],
+    deps = [
+        "//hack/lib",
+    ],
+)
+
+sh_library(
+    name = "test-cmd-util",
+    srcs = [
+        "test-cmd-util.sh",
+    ],
+    data = ["//pkg/kubectl/validation:testdata/v1/validPod.yaml"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

hack/make-rules/test-cmd-util.sh

@@ -687,7 +687,7 @@ run_pod_tests() {
   kube::test::get_object_assert pods "{{range.items}}{{$id_field}}:{{end}}" 'valid-pod:'
 
   ## Patch can modify a local object
-  kubectl patch --local -f pkg/api/validation/testdata/v1/validPod.yaml --patch='{"spec": {"restartPolicy":"Never"}}' -o jsonpath='{.spec.restartPolicy}' | grep -q "Never"
+  kubectl patch --local -f pkg/kubectl/validation/testdata/v1/validPod.yaml --patch='{"spec": {"restartPolicy":"Never"}}' -o jsonpath='{.spec.restartPolicy}' | grep -q "Never"
 
   ## Patch pod can change image
   # Command