Remove find_engine_commit.dart, which is unused in the monorepo. (#164494)

Just cleanup of unused code.

dev/tools/bin/GITHUB_ACTIONS.md

@@ -1 +0,0 @@
-This is a stub-file that can be deleted.

dev/tools/find_engine_commit.dart

@@ -1,120 +0,0 @@
-// Copyright 2014 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.
-
-import 'dart:io';
-
-void _validate(List<String> args) {
-  bool errors = false;
-  if (!File('bin/cache/engine.stamp').existsSync()) {
-    errors = true;
-    print('This program must be run from the root of your flutter repository.');
-  }
-  if (!File('../engine/src/flutter/DEPS').existsSync()) {
-    errors = true;
-    print(
-      'This program assumes the engine directory is a sibling to the flutter repository directory.',
-    );
-  }
-  if (args.length != 1) {
-    errors = true;
-    print('This program takes the engine revision as a single argument.');
-  }
-  if (errors) {
-    exit(-1);
-  }
-}
-
-const String engineRepo = '../engine/src/flutter';
-
-Future<void> main(List<String> args) async {
-  _validate(args);
-  await _fetchUpstream();
-  await _fetchUpstream(engineRepo);
-  String? flutterRevision;
-  await for (final FlutterEngineRevision revision in _logEngineVersions()) {
-    if (!await containsRevision(args[0], revision.engineRevision)) {
-      if (flutterRevision == null) {
-        print('Revision not found.');
-        exit(-1);
-      }
-      print('earliest revision: $flutterRevision');
-      print('Tags that contain this engine revision:');
-      print(await _tagsForRevision(flutterRevision));
-      exit(0);
-    }
-    flutterRevision = revision.flutterRevision;
-  }
-}
-
-Future<void> _fetchUpstream([String workingDirectory = '.']) async {
-  print(
-    'Fetching remotes for "$workingDirectory" - you may be prompted for SSH credentials by git.',
-  );
-  final ProcessResult fetchResult = await Process.run('git', <String>[
-    'fetch',
-    '--all',
-  ], workingDirectory: workingDirectory);
-  if (fetchResult.exitCode != 0) {
-    throw Exception('Failed to fetch upstream in repository $workingDirectory');
-  }
-}
-
-Future<String> _tagsForRevision(String flutterRevision) async {
-  final ProcessResult tagResult = await Process.run('git', <String>[
-    'tag',
-    '--contains',
-    flutterRevision,
-  ]);
-  return tagResult.stdout as String;
-}
-
-Future<bool> containsRevision(String ancestorRevision, String revision) async {
-  final ProcessResult result = await Process.run('git', <String>[
-    'merge-base',
-    '--is-ancestor',
-    ancestorRevision,
-    revision,
-  ], workingDirectory: engineRepo);
-  return result.exitCode == 0;
-}
-
-Stream<FlutterEngineRevision> _logEngineVersions() async* {
-  final ProcessResult result = await Process.run('git', <String>[
-    'log',
-    '--oneline',
-    '-p',
-    '--',
-    'bin/internal/engine.version',
-  ]);
-  if (result.exitCode != 0) {
-    print(result.stderr);
-    throw Exception('Failed to log bin/internal/engine.version');
-  }
-
-  final List<String> lines = (result.stdout as String).split('\n');
-  int index = 0;
-  while (index < lines.length - 1) {
-    final String flutterRevision = lines[index].split(' ').first;
-    index += 1;
-    while (!lines[index].startsWith('+') || lines[index].startsWith('+++')) {
-      index += 1;
-    }
-    if (index >= lines.length) {
-      break;
-    }
-    final String engineRevision = lines[index].substring(1);
-    yield FlutterEngineRevision(flutterRevision, engineRevision);
-    index += lines[index + 1].startsWith(r'\ ') ? 2 : 1;
-  }
-}
-
-class FlutterEngineRevision {
-  const FlutterEngineRevision(this.flutterRevision, this.engineRevision);
-
-  final String flutterRevision;
-  final String engineRevision;
-
-  @override
-  String toString() => '$flutterRevision: $engineRevision';
-}