GitHub Actions: Add hadolint problem matcher (#37494)

.github/workflows/ci.yaml

@@ -207,6 +207,9 @@ jobs:
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@v2
+      - name: Register hadolint problem matcher
+        run: |
+          echo "::add-matcher::.github/workflows/matchers/hadolint.json"
       - name: Check Dockerfile
         uses: docker://hadolint/hadolint:v1.18.0
         with:

.github/workflows/matchers/hadolint.json

@@ -0,0 +1,16 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "hadolint",
+      "pattern": [
+        {
+          "regexp": "^(.+):(\\d+)\\s+((DL\\d{4}).+)$",
+          "file": 1,
+          "line": 2,
+          "message": 3,
+          "code": 4
+        }
+      ]
+    }
+  ]
+}