CI: Use workflow_run to trigger scheduled builds and static analysis.

Scheduled builds now are triggered by a dummy "scheduled" workflow that is invoked by the timer. This gives forks an ability to disable scheduled builds while maintaining ability to perform CI builds in forked repository. Similarly static analysis is invoked on completion of "build" workflow, ensuring analysis is performed with every build. Also should build workflow triggers change, we do not need to replicate same changes in static analysis workflow file.

.github/workflows/scheduled.yml

@@ -0,0 +1,15 @@
+#
+# This is a dummy workflow used to trigger scheduled builds. Forked repositories most likely should disable this
+# workflow to avoid daily builds of inactive repositories.
+#
+name: scheduled
+
+on:
+  schedule:
+    - cron:  '0 9 * * *'
+
+jobs:
+  scheduled:
+    runs-on: ubuntu-latest
+    steps:
+      - run: exit 0