add e2e-flakiness-detector GitHub action

Every day at 1400 UTC, this action runs the e2e tests many times (10 times per test case) to detect intermittent flakiness proactively instead of having it be occasionally detected in unrelated PRs. This information will help us fix flaky e2e tests.

.github/workflows/e2e-flakiness-detector.yml

@@ -0,0 +1,45 @@
+# Runs the e2e tests many times to detect intermittent flakiness proactively instead of having it be
+# occasionally detected in unrelated PRs.
+name: e2e-flakiness-detector
+
+on:
+  schedule:
+    - cron: '0 14 * * *' # daily at 1400 UTC
+  workflow_dispatch:
+
+jobs:
+  test-e2e:
+    strategy:
+      fail-fast: false
+      matrix:
+        runner: [ubuntu, windows]
+    runs-on: ${{ matrix.runner }}-latest
+    timeout-minutes: 15
+    permissions:
+      id-token: write
+      contents: read
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-node@v3
+        with:
+          node-version-file: .tool-versions
+      - uses: pnpm/action-setup@d882d12c64e032187b2edb46d3a0d003b7a43598 # SECURITY: pin third-party action hashes
+      - run: echo "STORE_PATH=$(pnpm store path)" >> $GITHUB_OUTPUT
+        shell: bash
+        id: pnpm-cache
+      - name: Cache pnpm store
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: ${{ runner.os }}-pnpm-store-
+      - run: pnpm install
+      - run: xvfb-run -a pnpm -C vscode run test:e2e --repeat-each 10 --retries 0
+        if: matrix.runner == 'ubuntu'
+      - run: pnpm -C vscode run test:e2e --repeat-each 10 --retries 0
+        if: matrix.runner != 'ubuntu'
+      - uses: actions/upload-artifact@v3
+        if: ${{ failure() }}
+        with:
+          name: playwright-recordings ${{ matrix.runner }}
+          path: playwright/**/*.webm