add github workflow to cpplint costmap_3d

Add cpplint for costmap_3d. Currently only the costmap_3d package
passes, so only check it.

.github/workflows/workflow.yaml

@@ -0,0 +1,20 @@
+name: lint
+on: [push]
+
+defaults:
+  run:
+    # Only lint the costmap_3d package, the rest are upstream and have many
+    # linter errors that there is little point in fixing.
+    working-directory: ./costmap_3d
+jobs:
+  lint:
+    name: Badger Linting
+    runs-on:
+      - self-hosted
+      - k8s
+    steps:
+      - name: Run Linting
+        uses: BadgerTechnologies/ros-ci-docker/linter@linter-v1
+        with:
+          HARBOR_USER: ${{ secrets.HARBOR_USER }}
+          HARBOR_PASS: ${{ secrets.HARBOR_PASS }}