[VOL-1866] Changed module dependency to v12.0.0 of k8s client-go and v1.15.4 of k8s api/apimachinery in sync with other voltha components

Had to use pseudo-version corresponding to v12.0.0 of k8s client-go
because golang proxy is no longer serving the modules not complying
to Semantic Import Versioning rules including client-go v12.0.0.
Refer to https://github.com/kubernetes/client-go/issues/631 and
https://github.com/golang/go/issues/33558

Change-Id: I2e558bab7f0702f230761319eb5392a7d0532ea3
diff --git a/vendor/k8s.io/api/node/v1beta1/generated.proto b/vendor/k8s.io/api/node/v1beta1/generated.proto
new file mode 100644
index 0000000..9082fbd
--- /dev/null
+++ b/vendor/k8s.io/api/node/v1beta1/generated.proto
@@ -0,0 +1,66 @@
+/*
+Copyright 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.
+*/
+
+
+// This file was autogenerated by go-to-protobuf. Do not edit it manually!
+
+syntax = 'proto2';
+
+package k8s.io.api.node.v1beta1;
+
+import "k8s.io/apimachinery/pkg/apis/meta/v1/generated.proto";
+import "k8s.io/apimachinery/pkg/runtime/generated.proto";
+import "k8s.io/apimachinery/pkg/runtime/schema/generated.proto";
+
+// Package-wide variables from generator "generated".
+option go_package = "v1beta1";
+
+// RuntimeClass defines a class of container runtime supported in the cluster.
+// The RuntimeClass is used to determine which container runtime is used to run
+// all containers in a pod. RuntimeClasses are (currently) manually defined by a
+// user or cluster provisioner, and referenced in the PodSpec. The Kubelet is
+// responsible for resolving the RuntimeClassName reference before running the
+// pod.  For more details, see
+// https://git.k8s.io/enhancements/keps/sig-node/runtime-class.md
+message RuntimeClass {
+  // More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata
+  // +optional
+  optional k8s.io.apimachinery.pkg.apis.meta.v1.ObjectMeta metadata = 1;
+
+  // Handler specifies the underlying runtime and configuration that the CRI
+  // implementation will use to handle pods of this class. The possible values
+  // are specific to the node & CRI configuration.  It is assumed that all
+  // handlers are available on every node, and handlers of the same name are
+  // equivalent on every node.
+  // For example, a handler called "runc" might specify that the runc OCI
+  // runtime (using native Linux containers) will be used to run the containers
+  // in a pod.
+  // The Handler must conform to the DNS Label (RFC 1123) requirements, and is
+  // immutable.
+  optional string handler = 2;
+}
+
+// RuntimeClassList is a list of RuntimeClass objects.
+message RuntimeClassList {
+  // Standard list metadata.
+  // More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata
+  // +optional
+  optional k8s.io.apimachinery.pkg.apis.meta.v1.ListMeta metadata = 1;
+
+  // Items is a list of schema objects.
+  repeated RuntimeClass items = 2;
+}
+