Bazel-ify most of the Python scripts. (#229)

github_tools/BUILD

@@ -0,0 +1,43 @@
+# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+# Exceptions. See /LICENSE for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+load("@rules_python//python:defs.bzl", "py_binary", "py_library", "py_test")
+
+py_library(
+    name = "github_helpers",
+    srcs = ["github_helpers.py"],
+)
+
+py_test(
+    name = "github_helpers_test",
+    srcs = ["github_helpers_test.py"],
+    deps = [":github_helpers"],
+)
+
+py_binary(
+    name = "pr_comments",
+    srcs = ["pr_comments.py"],
+    deps = ["github_helpers"],
+)
+
+py_test(
+    name = "pr_comments_test",
+    srcs = ["pr_comments_test.py"],
+    deps = [":pr_comments"],
+)
+
+py_binary(
+    name = "update_label_access",
+    srcs = ["update_label_access.py"],
+    deps = ["github_helpers"],
+)
+
+py_test(
+    name = "update_label_access_test",
+    srcs = ["update_label_access_test.py"],
+    deps = [
+        ":pr_comments",
+        ":update_label_access",
+    ],
+)