.github: add dependabot integration

Dependabot creates a PR for us so we have to introduce a new action
which updates node-modules for us.

.github/dependabot.yml

@@ -0,0 +1,19 @@
+version: 2
+updates:
+  - package-ecosystem: "npm"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    groups:
+      eslint:
+        patterns:
+          - "eslint*"
+      esbuild:
+        patterns:
+          - "esbuild*"
+      stylelint:
+        patterns:
+          - "stylelint*"
+      patternfly:
+        patterns:
+          - "@patternfly*"

.github/workflows/dependabot.yml

@@ -0,0 +1,39 @@
+name: Dependabot update node-modules
+on: pull_request
+
+permissions:
+  pull-requests: write
+
+jobs:
+  dependabot:
+    # 22.04's podman has issues with piping and causes tar errors
+    runs-on: ubuntu-20.04
+    if: ${{ github.actor == 'dependabot[bot]' }}
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v3
+
+      - name: Run npm-update bot
+        run: |
+          make tools/node-modules
+          git config --global user.name "GitHub Workflow"
+          git config --global user.email "[email protected]"
+          mkdir -p ~/.config/cockpit-dev
+          echo ${{ github.token }} >> ~/.config/cockpit-dev/github-token
+          eval $(ssh-agent)
+          ssh-add - <<< '${{ secrets.NODE_CACHE_DEPLOY_KEY }}'
+          ./tools/node-modules install
+          ./tools/node-modules push
+          git add node_modules
+          ssh-add -D
+          ssh-agent -k
+
+      - name: Force push the change to trigger testing workflows
+        run: |
+          sleep 1 # make sure the timestamp changes
+          git commit --amend --no-edit
+          eval $(ssh-agent)
+          ssh-add - <<< '${{ secrets.COCKPIT_DEPLOY_KEY }}'
+          git push --force '[email protected]:${{ github.repository }}' HEAD
+          ssh-add -D
+          ssh-agent -k