Add check for build warnings check (#11175)

Author: gewarren

.github/policies/auto-merge.yml

@@ -16,9 +16,8 @@ configuration:
             label: ':octocat: auto-merge'
         - targetsBranch:
             branch: main
-        - or:
-            - isActivitySender:
-                user: dotnet-policy-service[bot]
+        - isActivitySender:
+            user: dotnet-policy-service[bot]
       then:
         - enableAutoMerge:
             mergeMethod: Squash

.github/workflows/check-for-build-warnings.yml

@@ -0,0 +1,26 @@
+name: 'OPS status checker'
+
+on:
+  pull_request_target:
+    types: [opened, synchronize, reopened]
+
+permissions:
+  contents: read
+
+jobs:
+  status_checker_job:
+    name: Look for build warnings
+    runs-on: ubuntu-latest
+    permissions:
+        statuses: read
+        pull-requests: write
+    steps:
+    - name: Harden Runner
+      uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+      with:
+        egress-policy: audit
+
+    - uses: dotnet/docs-tools/actions/status-checker@main
+      with:
+        repo_token: ${{ secrets.GITHUB_TOKEN }}
+        mode: "warning"