Add Kokoro job to tag issues (#144)

.kokoro/release/tag-issues.cfg

@@ -0,0 +1,25 @@
+before_action {
+  fetch_keystore {
+    keystore_resource {
+      keystore_config_id: 73713
+      keyname: "yoshi-automation-github-key"
+    }
+  }
+}
+
+# Download trampoline resources.
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
+
+# Use the trampoline script to run in docker.
+build_file: "sloth/.kokoro/trampoline.sh"
+
+# Configure the docker image for kokoro-trampoline.
+env_vars: {
+    key: "TRAMPOLINE_IMAGE"
+    value: "gcr.io/cloud-devrel-kokoro-resources/node:10-user"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/sloth/.kokoro/tag-issues.sh"
+}

.kokoro/tag-issues.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+# Copyright 2018 Google LLC
+#
+# 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
+#
+#     https://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.
+
+set -eo pipefail
+
+export SLOTH_GITHUB_TOKEN=$(cat $KOKORO_KEYSTORE_DIR/73713_yoshi-automation-github-key)
+
+npx https://github.com/googleapis/sloth tag-issues