add .clang-tidy

Former-commit-id: e046cec15e65e06aaa1bed61df4c91ee54eae370

.clang-tidy

+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+---
+Checks:          'clang-diagnostic-*,clang-analyzer-*,-clang-analyzer-alpha*,google-*,modernize-*,readability-*'
+# produce HeaderFilterRegex from cpp/build-support/lint_exclusions.txt with:
+# echo -n '^('; sed -e 's/*/\.*/g' cpp/build-support/lint_exclusions.txt | tr '\n' '|'; echo ')$'
+HeaderFilterRegex: '^(.*cmake-build-debug.*|.*cmake-build-release.*|.*cmake_build.*|.*src/thirdparty.*|.*src/core/thirdparty.*|.*src/grpc.*|)$'
+AnalyzeTemporaryDtors: true
+CheckOptions:
+  - key:             google-readability-braces-around-statements.ShortStatementLines
+    value:           '1'
+  - key:             google-readability-function-size.StatementThreshold
+    value:           '800'
+  - key:             google-readability-namespace-comments.ShortNamespaceLines
+    value:           '10'
+  - key:             google-readability-namespace-comments.SpacesBeforeComments
+    value:           '2'