Add PR health workflow

.github/workflows/health.yaml

@@ -0,0 +1,14 @@
+name: Health
+on:
+  pull_request:
+    branches: [ main ]
+    types: [opened, synchronize, reopened, labeled, unlabeled]
+
+jobs:
+  health:
+    uses: dart-lang/ecosystem/.github/workflows/health.yaml@main
+    with:
+      coverage_web: false
+      sdk: dev
+    permissions:
+      pull-requests: write

.github/workflows/post_summaries.yaml

@@ -0,0 +1,17 @@
+name: Comment on the pull request
+
+on:
+  # Trigger this workflow after the Health workflow completes. This workflow will have permissions to
+  # do things like create comments on the PR, even if the original workflow couldn't.
+  workflow_run:
+    workflows: 
+      - Health
+      - Publish
+    types:
+      - completed
+
+jobs:
+  upload:
+    uses: dart-lang/ecosystem/.github/workflows/post_summaries.yaml@main
+    permissions:
+      pull-requests: write