devops: run webkit-wsl tests in headed and headless

Adds a workflow with two jobs that run the WebKit library and page tests
through the webkit-wsl channel on the self-hosted Windows runner, headed
and headless.

Reference: #37036

Author: yury-s

.github/workflows/tests_webkit_wsl.yml

@@ -0,0 +1,69 @@
+name: "tests webkit wsl"
+
+on:
+  push:
+    branches:
+      - main
+      - release-*
+  pull_request:
+    paths-ignore:
+      - 'browser_patches/**'
+      - 'docs/**'
+      - 'packages/playwright/src/mcp/**'
+      - 'tests/mcp/**'
+    branches:
+      - main
+      - release-*
+  workflow_dispatch:
+
+env:
+  # Force terminal colors. @see https://www.npmjs.com/package/colors
+  FORCE_COLOR: 1
+
+permissions:
+  id-token: write   # This is required for OIDC login (azure/login) to succeed
+  contents: read    # This is required for actions/checkout to succeed
+
+jobs:
+  test_webkit_wsl:
+    name: "Tests @ WebKit WSL ${{ matrix.headed && '(headed)' || '(headless)' }}"
+    runs-on: ["self-hosted", "1ES.Pool=DevDivPlaywrightWindows11"]
+    strategy:
+      fail-fast: false
+      matrix:
+        headed: [true, false]
+    steps:
+    - uses: actions/checkout@v6
+    - uses: actions/setup-node@v6
+      with:
+        node-version: 20
+    # WebKit in WSL only reaches servers on the Windows host with mirrored networking.
+    - name: Enable WSL2 networkingMode=mirrored
+      shell: powershell
+      run: Add-Content -Path $env:USERPROFILE\.wslconfig -Value "[wsl2]`nnetworkingMode=mirrored"
+    - run: npm ci
+      env:
+        DEBUG: pw:install
+        PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD: 1
+    - run: npm run build
+    - run: npx playwright install webkit-wsl ffmpeg
+    - name: Run tests
+      run: npm run wtest -- ${{ matrix.headed && '--headed' || '' }}
+      env:
+        PWTEST_CHANNEL: webkit-wsl
+        PW_TAG: "@webkit-wsl-${{ matrix.headed && 'headed' || 'headless' }}"
+    - name: Azure Login
+      if: always()
+      uses: azure/login@v2
+      with:
+        client-id: ${{ secrets.AZURE_FLAKINESS_DASHBOARD_CLIENT_ID }}
+        tenant-id: ${{ secrets.AZURE_FLAKINESS_DASHBOARD_TENANT_ID }}
+        subscription-id: ${{ secrets.AZURE_FLAKINESS_DASHBOARD_SUBSCRIPTION_ID }}
+    - run: ./utils/upload_flakiness_dashboard.sh ./test-results/report.json
+      if: always()
+      shell: bash
+    - uses: actions/upload-artifact@v7
+      if: ${{ !cancelled() }}
+      with:
+        name: webkit-wsl-${{ matrix.headed && 'headed' || 'headless' }}-results
+        path: test-results