add metomic workflow file (#81)

.github/workflows

@@ -0,0 +1,51 @@
+on:
+  pull_request:
+    types: [opened, reopened, synchronize]
+  pull_request_review_comment:
+    types: [created, edited, deleted]
+
+name: Metomic Scan
+
+jobs:
+  scan-secrets:
+    name: Scan For Secrets
+    runs-on: ubuntu-latest
+    steps:
+      - name: checkout-repo
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+
+      - name: authenticate-with-metomic
+        id: authenticate
+        continue-on-error: ${{ vars.METOMIC_FAIL_ON_CONNECTION_ERROR != 'TRUE' }}
+        run: |
+          curl -s --location --request GET '${{ vars.METOMIC_INTEGRATION_ENDPOINT }}/token' --header 'X-API-Key: ${{ secrets.METOMIC_API_TOKEN }}' -o .metomic_token.json
+          echo METOMIC_ACCESS_TOKEN=$(cat .metomic_token.json | jq -r -c '.accessToken') >> $GITHUB_OUTPUT
+          PASS=$(cat .metomic_token.json | jq -r -c '.accessToken // empty')
+          if [ -z "$PASS" ]; then
+            cat .metomic_token.json
+            echo ""
+            echo "FAIL: failed to fetch auth token from Metomic. Ensure required organisation variables / secrets are set correctly. METOMIC_INTEGRATION_ENDPOINT, METOMIC_API_TOKEN"
+            echo "The correct values for these variables are available from the installations page of the Metomic dashboard"
+            exit 1
+          fi
+
+      - name: checkout-metomic-action
+        id: checkout
+        uses: actions/checkout@v3
+        if: ${{ steps.authenticate.outcome == 'success' }}
+        continue-on-error: ${{ vars.METOMIC_FAIL_ON_CONNECTION_ERROR != 'TRUE' }}
+        with:
+          repository: metomic/metomic-github-integration-action.git
+          path: "./.metomic"
+          ref: "main"
+          token: ${{ steps.authenticate.outputs.METOMIC_ACCESS_TOKEN }}
+
+      - name: scan
+        uses: ./.metomic/.github/actions/scan-secrets
+        if: ${{ steps.authenticate.outputs.METOMIC_ACCESS_TOKEN && steps.checkout.outcome == 'success' }}
+        with:
+          metomic_endpoint: ${{ vars.METOMIC_INTEGRATION_ENDPOINT }}
+          metomic_api_token: ${{ secrets.METOMIC_API_TOKEN }}
+          head_ref: ${{ github.event.pull_request.head.sha }}