ci: add failure slack notifications to preflight workflow

Author: NickLarsenNZ

.github/workflows/preflight.yaml

@@ -96,3 +96,39 @@ jobs:
             --architecture "linux/${ARCH_FOR_PREFLIGHT}" \
             --executable ./preflight-linux-amd64 \
             --token "${{ secrets.RH_PYXIS_API_TOKEN }}" \
+
+  notify:
+    name: Failure Notification
+    needs: [preflight]
+    runs-on: ubuntu-latest
+    if: failure()
+    steps:
+      - uses: slackapi/slack-github-action@37ebaef184d7626c5f204ab8d3baff4262dd30f0 # v1.27.0
+        with:
+          channel-id: "C07UG6JH44F" # notifications-container-images
+          payload: |
+            {
+              "text": "*${{ github.workflow }}* failed",
+              "attachments": [
+                {
+                  "pretext": "See the details below for a summary of which job(s) failed.",
+                  "color": "#aa0000",
+                  "fields": [
+                    {
+                      "title": "Preflight",
+                      "short": true,
+                      "value": "${{ needs.preflight.result }}"
+                    }
+                  ],
+                  "actions": [
+                    {
+                      "type": "button",
+                      "text": "Go to workflow run",
+                      "url": "${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+                    }
+                  ]
+                }
+              ]
+            }
+        env:
+          SLACK_BOT_TOKEN: ${{ secrets.SLACK_CONTAINER_IMAGE_TOKEN }}