Adding workflow to check status of site used for daily smoke tests.

.github/workflows/smoke-test-daily-site-check.yml

@@ -0,0 +1,23 @@
+name: Check daily smoke test site status.
+on:
+  push:
+
+jobs:
+  ping_site:
+    runs-on: ubuntu-latest
+    name: Check site and notify if not found
+    steps:
+    - name: Check site status
+      id: sitecheck
+      uses: srt32/uptime@958231f4d95c117f08eb0fc70907e80d0dfedf2b
+      with:
+        url-to-hit: "${{ secrets.SMOKE_TEST_URL }}ready/"
+        expected-statuses: "200,301"
+    - name: Send message to Slack API
+      if: failure()
+      uses: archive/github-actions-slack@deecc2edc496dc642d643de1d7cf3a47f51fb27a
+      id: notify
+      with:
+        slack-bot-user-oauth-access-token: ${{ secrets.SMOKE_TEST_SLACK_TOKEN }}
+        slack-channel: ${{ secrets.SMOKE_TEST_SLACK_CHANNEL }}
+        slack-text: ':warning: <!subteam^${{ secrets.SMOKE_TEST_SLACK_GROUP }}> FYI the URL ${{ secrets.SMOKE_TEST_URL }}ready/ appears to be returning `404 not found` :x:'