[labeler] Add engine workflow (flutter/engine#42566)

https://github.com/flutter/flutter/issues/126002

engine/src/flutter/.github/labeler.yml

@@ -0,0 +1,34 @@
+# 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.
+
+# See https://github.com/actions/labeler/blob/main/README.md for docs.
+embedder:
+  - shell/platform/embedder
+
+impeller:
+  - impeller/**/*
+
+platform-android:
+  - shell/platform/android/**/*
+
+platform-ios:
+  - shell/platform/darwin/common/**/*
+  - shell/platform/darwin/ios/**/*
+
+platform-fuchsia:
+  - shell/platform/fuchsia/**/*
+
+platform-linux:
+  - shell/platform/linux/**/*
+
+platform-macos:
+  - shell/platform/darwin/common/**/*
+  - shell/platform/darwin/macos/**/*
+
+platform-web:
+  - lib/web_ui/**/*
+  - '**/web_sdk/**/*'
+
+platform-windows:
+  - shell/platform/windows/**/*

engine/src/flutter/.github/workflows/labeler.yml

@@ -0,0 +1,20 @@
+# 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.
+
+name: "Pull Request Labeler"
+on:
+- pull_request_target
+
+# Declare default permissions as read only.
+permissions: read-all
+
+jobs:
+  triage:
+    if: ${{ github.repository == 'flutter/flutter' }}
+    permissions:
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+    # Source available at https://github.com/actions/labeler/blob/main/README.md
+    - uses: actions/labeler@0776a679364a9a16110aac8d0f40f5e11009e327