Add CI health checks for DevTools packages (#9653)

Author: elliette

.github/workflows/health.yaml

@@ -0,0 +1,15 @@
+name: Health
+on:
+  pull_request:
+    branches: [ master ]
+    types: [opened, synchronize, reopened, labeled, unlabeled]
+jobs:
+  health:
+    uses: dart-lang/ecosystem/.github/workflows/health.yaml@main
+    with:
+        checks: "version,changelog,breaking,do-not-submit,leaking"
+        fail_on: "do-not-submit"
+        warn_on: "version,changelog,breaking,leaking"
+        use-flutter: true
+    permissions:
+        pull-requests: write

.github/workflows/post_summary.yaml

@@ -0,0 +1,16 @@
+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
+    types:
+      - completed
+
+jobs:
+  upload:
+    uses: dart-lang/ecosystem/.github/workflows/post_summaries.yaml@main
+    permissions:
+      pull-requests: write