[windows] Add a check for too long path names (#33418)

We should probably cap this so that our customers have a chance of
cloning the repository.

---------

Co-authored-by: ctiller <ctiller@users.noreply.github.com>

tools/distrib/check_path_length.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+
+# Copyright 2023 gRPC 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.
+
+import os
+import subprocess
+
+# Maximum path length for a path in the repository before we start seeing
+# problems with Windows cloning the repository. (kind of arbitrary, less than
+# Windows actual limit, but enough that we avoid problems).
+maxlen = 150
+
+errors = 0
+for path in subprocess.check_output(["git", "ls-files"]).decode().splitlines():
+    if len(path) > maxlen:
+        print(f"Path too long: {path}")
+        errors += 1
+
+if errors:
+    print(f"Found {errors} files with paths longer than {maxlen} characters")
+    exit(1)

tools/run_tests/sanity/sanity_tests.yaml

@@ -46,3 +46,4 @@
 - script: tools/run_tests/sanity/build_banned_constructs.sh
 - script: tools/distrib/check_redundant_namespace_qualifiers.py
 - script: tools/distrib/check_namespace_qualification.py
+- script: tools/distrib/check_path_length.py