revert: Re-add .github directory.

Copybara deleted it when it pushed a change before its config
was updated to ignore (and preserve) the .github directory.

This reverts commit a84cecb.

.bazelrc

@@ -0,0 +1,2 @@
+# Project-specific bazelrc settings
+# NOTE: While empty, this is referenced by the release workflow

.github/release.yml

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+changelog:
+  categories:
+    - title: Other Changes
+      labels:
+        - "*"

.github/workflows/ci.bazelrc

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+# This file contains Bazel settings to apply on CI only.
+
+# Debug where options came from
+build --announce_rc
+# This directory is configured in GitHub actions to be persisted between runs.
+build --disk_cache=~/.cache/bazel
+build --repository_cache=~/.cache/bazel-repo
+# Don't rely on test logs being easily accessible from the test runner,
+# though it makes the log noisier.
+test --test_output=errors
+# Allows tests to run bazelisk-in-bazel, since this is the cache folder used
+test --test_env=XDG_CACHE_HOME

.github/workflows/release.yml

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+# Copyright 2023 The Bazel Authors. All rights reserved.
+#
+# 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.
+
+# Cut a release whenever a new tag is pushed to the repo.
+name: Release
+
+on:
+  push:
+    tags:
+      - "v*.*.*"
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Mount bazel caches
+        uses: actions/cache@v3
+        with:
+          path: |
+            ~/.cache/bazel
+            ~/.cache/bazel-repo
+          key: bazel-cache-${{ hashFiles('**/BUILD.bazel', '**/*.bzl', 'WORKSPACE') }}
+          restore-keys: bazel-cache-
+      # Skipping tests for now to test the release workflow
+      # - name: bazel test //...
+      #   env:
+      #     # Bazelisk will download bazel to here
+      #     XDG_CACHE_HOME: ~/.cache/bazel-repo
+      #   run: bazel --bazelrc=.github/workflows/ci.bazelrc --bazelrc=.bazelrc test --keep_going //...
+      - name: Prepare workspace snippet
+        run: .github/workflows/workspace_snippet.sh ${{ env.GITHUB_REF_NAME }} > release_notes.txt
+      - name: Release
+        uses: softprops/action-gh-release@v1
+        with:
+          # Use GH feature to populate the changelog automatically
+          generate_release_notes: true
+          body_path: release_notes.txt
+          fail_on_unmatched_files: true
+          files: rules_testing-*.tar.gz

.github/workflows/workspace_snippet.sh

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+#!/usr/bin/env bash
+
+set -o errexit -o nounset -o pipefail
+
+# Set by GH actions, see
+# https://docs.github.com/en/actions/learn-github-actions/environment-variables#default-environment-variables
+TAG=${GITHUB_REF_NAME}
+PREFIX="rules_testing-${TAG:1}"
+ARCHIVE="rules_testing-$TAG.tar.gz"
+# The prefix is chosen to match what GitHub generates for source archives
+git archive --format=tar --prefix=${PREFIX}/ ${TAG} | gzip > $ARCHIVE
+SHA=$(shasum -a 256 $ARCHIVE | awk '{print $1}')
+
+cat << EOF
+WORKSPACE snippet:
+\`\`\`starlark
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+http_archive(
+    name = "rules_testing",
+    sha256 = "${SHA}",
+    strip_prefix = "${PREFIX}",
+    url = "https://github.com/bazelbuild/rules_testing/releases/download/${TAG}/${ARCHIVE}",
+)
+\`\`\`
+EOF