[ci] Migrate repo tooling from flutter/plugins (#3198)

Imports the repository tooling from flutter/plugins. This is being moved
in advance of the full repository merge in order to reduce the
complexity of the final merge, since it is highly separable from the
rest of the repository.

Rather than being a copy, this grafts the history of flutter/plugins's
script/tool directory (rewritten to exclude other directories), to
preserve `git blame` and related functionality. All of the commits here
except those from today are migrating the code as-is. My commits from
today:
- Replace all the CI usage of `flutter_plugin_tools` from pub with the
local copy, so that this PR tests the code being added.
- Updates documentation about the tool.
- Enables CI tests of the tool itself.
- Updates metadata for the tool (version, source repo).

Part of flutter/flutter#113764

Author: stuartmorgan-g

.ci/scripts/build_examples_win32.sh

@@ -3,5 +3,5 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-dart pub global run flutter_plugin_tools build-examples --windows \
+dart ./script/tool/bin/flutter_plugin_tools.dart build-examples --windows \
    --packages-for-branch --log-timing

.ci/scripts/create_all_packages_app.sh

@@ -3,5 +3,5 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-dart pub global run flutter_plugin_tools create-all-packages-app \
+dart ./script/tool/bin/flutter_plugin_tools.dart create-all-packages-app \
     --output-dir=. --exclude script/configs/exclude_all_packages_app.yaml

.ci/scripts/custom_package_tests.sh

@@ -8,6 +8,6 @@
 # script/configs/linux_only_custom_test.yaml
 #   Custom tests need Chrome. (They run in linux-custom_package_tests)
 
-dart pub global run flutter_plugin_tools custom-test \
+dart ./script/tool/bin/flutter_plugin_tools.dart custom-test \
    --packages-for-branch --log-timing \
    --exclude=script/configs/linux_only_custom_test.yaml

.ci/scripts/dart_unit_tests_win32.sh

@@ -3,5 +3,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-dart pub global run flutter_plugin_tools test --exclude=script/configs/windows_unit_tests_exceptions.yaml \
+dart ./script/tool/bin/flutter_plugin_tools.dart test \
+  --exclude=script/configs/windows_unit_tests_exceptions.yaml \
   --packages-for-branch --log-timing

.ci/scripts/drive_examples_win32.sh

@@ -3,5 +3,5 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-dart pub global run flutter_plugin_tools drive-examples --windows \
+dart ./script/tool/bin/flutter_plugin_tools.dart drive-examples --windows \
    --exclude=script/configs/exclude_integration_win32.yaml --packages-for-branch --log-timing

.ci/scripts/native_test_win32.sh

@@ -3,5 +3,5 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-dart pub global run flutter_plugin_tools native-test --windows \
+dart ./script/tool/bin/flutter_plugin_tools.dart native-test --windows \
    --no-integration --packages-for-branch --log-timing

.ci/scripts/plugin_tools_tests.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+cd script/tool
+dart pub run test

.ci/scripts/prepare_tool.sh

@@ -6,6 +6,5 @@
 # To set FETCH_HEAD for "git merge-base" to work
 git fetch origin main
 
-# Pinned version of the plugin tools, to avoid breakage in this repository
-# when pushing updates from flutter/plugins.
-dart pub global activate flutter_plugin_tools 0.13.4+2
+cd script/tool
+dart pub get

.ci/targets/plugin_tools_tests.yaml

@@ -0,0 +1,5 @@
+tasks:
+  - name: prepare tool
+    script: .ci/scripts/prepare_tool.sh
+  - name: tool unit tests
+    script: .ci/scripts/plugin_tools_tests.sh

.cirrus.yml

@@ -4,7 +4,7 @@ gcp_credentials: ENCRYPTED[!3a93d98d7c95a41f5033834ef30e50928fc5d81239dc632b153c
 only_if: $CIRRUS_TAG == '' && ($CIRRUS_PR != '' || $CIRRUS_BRANCH == 'main')
 env:
   CHANNEL: "master" # Default to master when not explicitly set by a task.
-  PLUGIN_TOOL_COMMAND: "dart pub global run flutter_plugin_tools"
+  PLUGIN_TOOL_COMMAND: "dart ./script/tool/bin/flutter_plugin_tools.dart"
 
 install_chrome_linux_template: &INSTALL_CHROME_LINUX
   env:
@@ -84,6 +84,10 @@ task:
     namespace: default
   matrix:
     ### Platform-agnostic tasks ###
+    - name: Linux plugin_tools_tests
+      script:
+        - cd script/tool
+        - dart pub run test
     # Repository rules and best-practice enforcement.
     # Only channel-agnostic tests should go here since it is only run once
     # (on Flutter master).
@@ -127,6 +131,9 @@ task:
         matrix:
           CHANNEL: "master"
           CHANNEL: "stable"
+      analyze_tool_script:
+        - cd script/tool
+        - dart analyze --fatal-infos
       analyze_script:
         # DO NOT change the custom-analysis argument here without changing the Dart repo.
         # See the comment in script/configs/custom_analysis.yaml for details.